implement the performance test in the Python test suite

Use the script like so, against the tenant to duplicate:

    poetry run python3 ./test_runner/duplicate_tenant.py 7ea51af32d42bfe7fb93bf5f28114d09  200 8

backup of pageserver.toml

    d =1
    pg_distrib_dir ='/home/admin/neon-main/pg_install'
    http_auth_type ='Trust'
    pg_auth_type ='Trust'
    listen_http_addr ='127.0.0.1:9898'
    listen_pg_addr ='127.0.0.1:64000'
    broker_endpoint ='http://127.0.0.1:50051/'
    #control_plane_api ='http://127.0.0.1:1234/'

    # Initial configuration file created by 'pageserver --init'
    #listen_pg_addr = '127.0.0.1:64000'
    #listen_http_addr = '127.0.0.1:9898'

    #wait_lsn_timeout = '60 s'
    #wal_redo_timeout = '60 s'

    #max_file_descriptors = 10000
    #page_cache_size = 160000

    # initial superuser role name to use when creating a new tenant
    #initial_superuser_name = 'cloud_admin'

    #broker_endpoint = 'http://127.0.0.1:50051'

    #log_format = 'plain'

    #concurrent_tenant_size_logical_size_queries = '1'

    #metric_collection_interval = '10 min'
    #cached_metric_collection_interval = '0s'
    #synthetic_size_calculation_interval = '10 min'

    #disk_usage_based_eviction = { max_usage_pct = .., min_avail_bytes = .., period = "10s"}

    #background_task_maximum_delay = '10s'

    [tenant_config]
    #checkpoint_distance = 268435456 # in bytes
    #checkpoint_timeout = 10 m
    #compaction_target_size = 134217728 # in bytes
    #compaction_period = '20 s'
    #compaction_threshold = 10

    #gc_period = '1 hr'
    #gc_horizon = 67108864
    #image_creation_threshold = 3
    #pitr_interval = '7 days'

    #min_resident_size_override = .. # in bytes
    #evictions_low_residence_duration_metric_threshold = '24 hour'
    #gc_feedback = false

    # make it determinsitic
    gc_period = '0s'
    checkpoint_timeout = '3650 day'
    compaction_period = '20 s'
    compaction_threshold = 10
    compaction_target_size = 134217728
    checkpoint_distance = 268435456
    image_creation_threshold = 3

    [remote_storage]
    local_path = '/home/admin/neon-main/bench_repo_dir/repo/remote_storage_local_fs'

remove http handler

switch to generalized rewrite_summary  & impl page_ctl subcommand to use it

WIP: change duplicate_tenant.py script to use the pagectl command

The script works but at restart, we detach the created tenants because
they're not known to the attachment service:

  Detaching tenant, control plane omitted it in re-attach response tenant_id=1e399d390e3aee6b11c701cbc716bb6c

=> figure out how to further integrate this

Cargo.lock

@@ -2634,6 +2634,16 @@ dependencies = [
  "winapi",
 ]
 
+[[package]]
+name = "nu-ansi-term"
+version = "0.46.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77a8165726e8236064dbb45459242600304b42a5ea24ee2948e18e023bf7ba84"
+dependencies = [
+ "overload",
+ "winapi",
+]
+
 [[package]]
 name = "num-bigint"
 version = "0.4.3"
@@ -2894,6 +2904,12 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4030760ffd992bef45b0ae3f10ce1aba99e33464c90d14dd7c039884963ddc7a"
 
+[[package]]
+name = "overload"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b15813163c1d831bf4a13c3610c05c0d03b39feb07f7e09fa234dac9b15aaf39"
+
 [[package]]
 name = "pagectl"
 version = "0.1.0"
@@ -2979,10 +2995,12 @@ dependencies = [
  "tokio",
  "tokio-io-timeout",
  "tokio-postgres",
+ "tokio-stream",
  "tokio-tar",
  "tokio-util",
  "toml_edit",
  "tracing",
+ "tracing-subscriber",
  "url",
  "utils",
  "walkdir",
@@ -5290,6 +5308,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "30a651bc37f915e81f087d86e62a18eec5f79550c7faff886f7090b4ea757c77"
 dependencies = [
  "matchers",
+ "nu-ansi-term",
  "once_cell",
  "regex",
  "serde",

libs/pageserver_api/src/key.rs

@@ -140,3 +140,36 @@ impl Key {
         })
     }
 }
+
+
+impl std::str::FromStr for Key {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        Self::from_hex(s)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::str::FromStr;
+
+    use crate::repository::Key;
+
+    #[test]
+    fn display_fromstr_bijection() {
+        let mut rng = rand::thread_rng();
+        use rand::Rng;
+
+        let key = Key {
+            field1: rng.gen(),
+            field2: rng.gen(),
+            field3: rng.gen(),
+            field4: rng.gen(),
+            field5: rng.gen(),
+            field6: rng.gen(),
+        };
+
+        assert_eq!(key, Key::from_str(&format!("{key}")).unwrap());
+    }
+}

libs/pageserver_api/src/models.rs

@@ -18,7 +18,7 @@ use utils::{
 
 use crate::{reltag::RelTag, shard::TenantShardId};
 use anyhow::bail;
-use bytes::{BufMut, Bytes, BytesMut};
+use bytes::{Buf, BufMut, Bytes, BytesMut};
 
 /// The state of a tenant in this pageserver.
 ///
@@ -371,6 +371,8 @@ pub struct TenantInfo {
     /// If a layer is present in both local FS and S3, it counts only once.
     pub current_physical_size: Option<u64>, // physical size is only included in `tenant_status` endpoint
     pub attachment_status: TenantAttachmentStatus,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub generation: Option<u32>,
 }
 
 /// This represents the output of the "timeline_detail" and "timeline_list" API calls.
@@ -515,6 +517,8 @@ pub enum HistoricLayerInfo {
         lsn_end: Lsn,
         remote: bool,
         access_stats: LayerAccessStats,
+
+        remote_path: Option<String>,
     },
     Image {
         layer_file_name: String,
@@ -523,6 +527,8 @@ pub enum HistoricLayerInfo {
         lsn_start: Lsn,
         remote: bool,
         access_stats: LayerAccessStats,
+
+        remote_path: Option<String>,
     },
 }
 
@@ -767,6 +773,36 @@ impl PagestreamBeMessage {
 
         bytes.into()
     }
+
+    pub fn deserialize(buf: Bytes) -> anyhow::Result<Self> {
+        let mut buf = buf.reader();
+        let msg_tag = buf.read_u8()?;
+        match msg_tag {
+            100 => todo!(),
+            101 => todo!(),
+            102 => {
+                let buf = buf.get_ref();
+                /* TODO use constant */
+                if buf.len() == 8192 {
+                    Ok(PagestreamBeMessage::GetPage(PagestreamGetPageResponse {
+                        page: buf.clone(),
+                    }))
+                } else {
+                    anyhow::bail!("invalid page size: {}", buf.len());
+                }
+            }
+            103 => {
+                let buf = buf.get_ref();
+                let cstr = std::ffi::CStr::from_bytes_until_nul(buf)?;
+                let rust_str = cstr.to_str()?;
+                Ok(PagestreamBeMessage::Error(PagestreamErrorResponse {
+                    message: rust_str.to_owned(),
+                }))
+            }
+            104 => todo!(),
+            _ => bail!("unknown tag: {:?}", msg_tag),
+        }
+    }
 }
 
 #[cfg(test)]
@@ -832,6 +868,7 @@ mod tests {
             state: TenantState::Active,
             current_physical_size: Some(42),
             attachment_status: TenantAttachmentStatus::Attached,
+            generation: None,
         };
         let expected_active = json!({
             "id": original_active.id.to_string(),
@@ -852,6 +889,7 @@ mod tests {
             },
             current_physical_size: Some(42),
             attachment_status: TenantAttachmentStatus::Attached,
+            generation: None,
         };
         let expected_broken = json!({
             "id": original_broken.id.to_string(),

libs/remote_storage/src/lib.rs

@@ -81,6 +81,12 @@ impl std::fmt::Display for RemotePath {
     }
 }
 
+impl From<RemotePath> for String {
+    fn from(val: RemotePath) -> Self {
+        val.0.into()
+    }
+}
+
 impl RemotePath {
     pub fn new(relative_path: &Utf8Path) -> anyhow::Result<Self> {
         anyhow::ensure!(
@@ -102,7 +108,7 @@ impl RemotePath {
         self.0.file_name()
     }
 
-    pub fn join(&self, segment: &Utf8Path) -> Self {
+    pub fn join<P: AsRef<Utf8Path>>(&self, segment: P) -> Self {
         Self(self.0.join(segment))
     }
 

pageserver/Cargo.toml

@@ -82,6 +82,8 @@ enum-map.workspace = true
 enumset.workspace = true
 strum.workspace = true
 strum_macros.workspace = true
+tokio-stream.workspace = true
+tracing-subscriber = { version = "0.3.17", features = ["env-filter"] }
 
 [dev-dependencies]
 criterion.workspace = true

pageserver/ctl/src/layers.rs

@@ -1,13 +1,15 @@
 use std::path::{Path, PathBuf};
 
 use anyhow::Result;
-use camino::Utf8Path;
+use camino::{Utf8Path, Utf8PathBuf};
 use clap::Subcommand;
 use pageserver::context::{DownloadBehavior, RequestContext};
 use pageserver::task_mgr::TaskKind;
 use pageserver::tenant::block_io::BlockCursor;
 use pageserver::tenant::disk_btree::DiskBtreeReader;
 use pageserver::tenant::storage_layer::delta_layer::{BlobRef, Summary};
+use pageserver::tenant::storage_layer::{delta_layer, image_layer};
+use pageserver::tenant::storage_layer::{DeltaLayer, ImageLayer};
 use pageserver::tenant::{TENANTS_SEGMENT_NAME, TIMELINES_SEGMENT_NAME};
 use pageserver::{page_cache, virtual_file};
 use pageserver::{
@@ -20,6 +22,7 @@ use pageserver::{
 };
 use std::fs;
 use utils::bin_ser::BeSer;
+use utils::id::{TenantId, TimelineId};
 
 use crate::layer_map_analyzer::parse_filename;
 
@@ -45,6 +48,13 @@ pub(crate) enum LayerCmd {
         /// The id from list-layer command
         id: usize,
     },
+    RewriteSummary {
+        layer_file_path: Utf8PathBuf,
+        #[clap(long)]
+        new_tenant_id: Option<TenantId>,
+        #[clap(long)]
+        new_timeline_id: Option<TimelineId>,
+    },
 }
 
 async fn read_delta_file(path: impl AsRef<Path>, ctx: &RequestContext) -> Result<()> {
@@ -100,6 +110,7 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
                     println!("- timeline {}", timeline.file_name().to_string_lossy());
                 }
             }
+            Ok(())
         }
         LayerCmd::ListLayer {
             path,
@@ -128,6 +139,7 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
                     idx += 1;
                 }
             }
+            Ok(())
         }
         LayerCmd::DumpLayer {
             path,
@@ -168,7 +180,63 @@ pub(crate) async fn main(cmd: &LayerCmd) -> Result<()> {
                     idx += 1;
                 }
             }
+            Ok(())
+        }
+        LayerCmd::RewriteSummary {
+            layer_file_path,
+            new_tenant_id,
+            new_timeline_id,
+        } => {
+            pageserver::virtual_file::init(10);
+            pageserver::page_cache::init(100);
+
+            let ctx = RequestContext::new(TaskKind::DebugTool, DownloadBehavior::Error);
+
+            macro_rules! rewrite_closure {
+                ($($summary_ty:tt)*) => {{
+                    |summary| $($summary_ty)* {
+                        tenant_id: new_tenant_id.unwrap_or(summary.tenant_id),
+                        timeline_id: new_timeline_id.unwrap_or(summary.timeline_id),
+                        ..summary
+                    }
+                }};
+            }
+
+            let res = ImageLayer::rewrite_summary(
+                layer_file_path,
+                rewrite_closure!(image_layer::Summary),
+                &ctx,
+            )
+            .await;
+            match res {
+                Ok(()) => {
+                    println!("Successfully rewrote summary of image layer {layer_file_path}");
+                    return Ok(());
+                }
+                Err(image_layer::RewriteSummaryError::MagicMismatch) => (), // fallthrough
+                Err(image_layer::RewriteSummaryError::Other(e)) => {
+                    return Err(e);
+                }
+            }
+
+            let res = DeltaLayer::rewrite_summary(
+                layer_file_path,
+                rewrite_closure!(delta_layer::Summary),
+                &ctx,
+            )
+            .await;
+            match res {
+                Ok(()) => {
+                    println!("Successfully rewrote summary of delta layer {layer_file_path}");
+                    return Ok(());
+                }
+                Err(delta_layer::RewriteSummaryError::MagicMismatch) => (), // fallthrough
+                Err(delta_layer::RewriteSummaryError::Other(e)) => {
+                    return Err(e);
+                }
+            }
+
+            anyhow::bail!("not an image or delta layer: {layer_file_path}");
         }
     }
-    Ok(())
 }

pageserver/src/bin/getpage_bench_libpq.rs

@@ -0,0 +1,416 @@
+use anyhow::Context;
+use clap::Parser;
+
+use pageserver::pgdatadir_mapping::{is_rel_block_key, key_to_rel_block};
+use pageserver::repository;
+
+use pageserver_api::reltag::RelTag;
+use rand::prelude::*;
+use tokio::sync::Barrier;
+use tracing::info;
+use utils::id::{TenantId, TimelineId};
+use utils::logging;
+
+use std::future::Future;
+
+use std::sync::atomic::{AtomicU64, Ordering};
+use std::sync::Arc;
+
+use tokio::task::JoinHandle;
+
+struct Key(repository::Key);
+
+impl std::str::FromStr for Key {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        repository::Key::from_hex(s).map(Key)
+    }
+}
+
+struct KeyRange {
+    start: i128,
+    end: i128,
+}
+
+impl KeyRange {
+    fn len(&self) -> i128 {
+        self.end - self.start
+    }
+}
+
+struct RelTagBlockNo {
+    rel_tag: RelTag,
+    block_no: u32,
+}
+
+#[derive(clap::Parser)]
+struct Args {
+    #[clap(long, default_value = "http://localhost:9898")]
+    mgmt_api_endpoint: String,
+    #[clap(long, default_value = "postgres://postgres@localhost:64000")]
+    page_service_connstring: String,
+    // tenant_id: String,
+    // timeline_id: String,
+    #[clap(long)]
+    num_tasks: usize,
+    #[clap(long)]
+    num_requests: usize,
+    #[clap(long)]
+    pick_n_tenants: Option<usize>,
+    tenants: Option<Vec<TenantId>>,
+}
+
+#[derive(Debug, Default)]
+struct LiveStats {
+    completed_requests: AtomicU64,
+}
+
+impl LiveStats {
+    fn inc(&self) {
+        self.completed_requests.fetch_add(1, Ordering::Relaxed);
+    }
+}
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    logging::init(
+        logging::LogFormat::Plain,
+        logging::TracingErrorLayerEnablement::Disabled,
+        logging::Output::Stderr,
+    )
+    .unwrap();
+
+    let args: &'static Args = Box::leak(Box::new(Args::parse()));
+
+    let client = Arc::new(mgmt_api_client::Client::new(args.mgmt_api_endpoint.clone()));
+
+    let mut tenants: Vec<TenantId> = if let Some(tenants) = &args.tenants {
+        tenants.clone()
+    } else {
+        client
+            .list_tenants()
+            .await?
+            .into_iter()
+            .map(|ti| ti.id)
+            .collect()
+    };
+    let tenants = if let Some(n) = args.pick_n_tenants {
+        tenants.truncate(n);
+        if tenants.len() != n {
+            anyhow::bail!("too few tenants: {} < {}", tenants.len(), n);
+        }
+        tenants
+    } else {
+        tenants
+    };
+
+    let mut tenant_timelines = Vec::new();
+    for tenant_id in tenants {
+        tenant_timelines.extend(
+            client
+                .list_timelines(tenant_id)
+                .await?
+                .into_iter()
+                .map(|ti| (tenant_id, ti.timeline_id)),
+        );
+    }
+    info!("tenant_timelines:\n{:?}", tenant_timelines);
+
+    let stats = Arc::new(LiveStats::default());
+
+    let num_work_tasks = tenant_timelines.len() * args.num_tasks;
+
+    let start_work_barrier = Arc::new(tokio::sync::Barrier::new(num_work_tasks + 1));
+
+    tokio::spawn({
+        let stats = Arc::clone(&stats);
+        let start_work_barrier = Arc::clone(&start_work_barrier);
+        async move {
+            start_work_barrier.wait().await;
+            loop {
+                let start = std::time::Instant::now();
+                tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+                let completed_requests = stats.completed_requests.swap(0, Ordering::Relaxed);
+                let elapsed = start.elapsed();
+                info!(
+                    "RPS: {:.0}",
+                    completed_requests as f64 / elapsed.as_secs_f64()
+                );
+            }
+        }
+    });
+
+    let mut tasks = Vec::new();
+    for (tenant_id, timeline_id) in tenant_timelines {
+        let stats = Arc::clone(&stats);
+        let t = tokio::spawn(timeline(
+            args,
+            client.clone(),
+            tenant_id,
+            timeline_id,
+            Arc::clone(&start_work_barrier),
+            stats,
+        ));
+        tasks.push(t);
+    }
+
+    for t in tasks {
+        t.await.unwrap().unwrap();
+    }
+
+    anyhow::Ok(())
+}
+
+fn timeline(
+    args: &'static Args,
+    mgmt_api_client: Arc<mgmt_api_client::Client>,
+    tenant_id: TenantId,
+    timeline_id: TimelineId,
+    start_work_barrier: Arc<Barrier>,
+    stats: Arc<LiveStats>,
+) -> impl Future<Output = anyhow::Result<()>> + Send + Sync {
+    async move {
+        let partitioning = mgmt_api_client.keyspace(tenant_id, timeline_id).await?;
+        let lsn = partitioning.at_lsn;
+        let ranges = partitioning
+            .keys
+            .ranges
+            .iter()
+            .filter_map(|r| {
+                let start = r.start;
+                let end = r.end;
+                // filter out non-relblock keys
+                match (is_rel_block_key(start), is_rel_block_key(end)) {
+                    (true, true) => Some(KeyRange {
+                        start: start.to_i128(),
+                        end: end.to_i128(),
+                    }),
+                    (true, false) | (false, true) => {
+                        unimplemented!("split up range")
+                    }
+                    (false, false) => None,
+                }
+            })
+            .collect::<Vec<_>>();
+
+        // weighted ranges
+        let weights = ranges.iter().map(|r| r.len()).collect::<Vec<_>>();
+
+        let ranges = Arc::new(ranges);
+        let weights = Arc::new(weights);
+
+        let mut tasks = Vec::<JoinHandle<()>>::new();
+
+        for _i in 0..args.num_tasks {
+            let ranges = ranges.clone();
+            let _weights = weights.clone();
+            let start_work_barrier = Arc::clone(&start_work_barrier);
+            let task = tokio::spawn({
+                let stats = Arc::clone(&stats);
+                async move {
+                    let mut getpage_client = getpage_client::Client::new(
+                        args.page_service_connstring.clone(),
+                        tenant_id,
+                        timeline_id,
+                    )
+                    .await
+                    .unwrap();
+                    start_work_barrier.wait().await;
+                    for _i in 0..args.num_requests {
+                        let key = {
+                            let mut rng = rand::thread_rng();
+                            let r = ranges.choose_weighted(&mut rng, |r| r.len()).unwrap();
+                            let key: i128 = rng.gen_range(r.start..r.end);
+                            let key = repository::Key::from_i128(key);
+                            // XXX filter these out when we iterate the keyspace
+                            assert!(
+                                is_rel_block_key(key),
+                                "we filter non-relblock keys out above"
+                            );
+                            let (rel_tag, block_no) =
+                                key_to_rel_block(key).expect("we just checked");
+                            RelTagBlockNo { rel_tag, block_no }
+                        };
+                        getpage_client
+                            .getpage(key, lsn)
+                            .await
+                            .with_context(|| {
+                                format!("getpage for tenant {} timeline {}", tenant_id, timeline_id)
+                            })
+                            .unwrap();
+                        stats.inc();
+                    }
+                    getpage_client.shutdown().await;
+                }
+            });
+            tasks.push(task);
+        }
+
+        for task in tasks {
+            task.await.unwrap();
+        }
+
+        Ok(())
+    }
+}
+
+mod mgmt_api_client {
+    use anyhow::Context;
+
+    use hyper::{client::HttpConnector, Uri};
+    use utils::id::{TenantId, TimelineId};
+
+    pub(crate) struct Client {
+        mgmt_api_endpoint: String,
+        pub(crate) client: hyper::Client<HttpConnector, hyper::Body>,
+    }
+
+    impl Client {
+        pub fn new(mgmt_api_endpoint: String) -> Self {
+            Self {
+                mgmt_api_endpoint,
+                client: hyper::client::Client::new(),
+            }
+        }
+
+        pub async fn list_tenants(
+            &self,
+        ) -> anyhow::Result<Vec<pageserver_api::models::TenantInfo>> {
+            let uri = Uri::try_from(format!("{}/v1/tenant", self.mgmt_api_endpoint))?;
+            let resp = self.client.get(uri).await?;
+            if !resp.status().is_success() {
+                anyhow::bail!("status error");
+            }
+            let body = hyper::body::to_bytes(resp).await?;
+            Ok(serde_json::from_slice(&body)?)
+        }
+
+        pub async fn list_timelines(
+            &self,
+            tenant_id: TenantId,
+        ) -> anyhow::Result<Vec<pageserver_api::models::TimelineInfo>> {
+            let uri = Uri::try_from(format!(
+                "{}/v1/tenant/{tenant_id}/timeline",
+                self.mgmt_api_endpoint
+            ))?;
+            let resp = self.client.get(uri).await?;
+            if !resp.status().is_success() {
+                anyhow::bail!("status error");
+            }
+            let body = hyper::body::to_bytes(resp).await?;
+            Ok(serde_json::from_slice(&body)?)
+        }
+
+        pub async fn keyspace(
+            &self,
+            tenant_id: TenantId,
+            timeline_id: TimelineId,
+        ) -> anyhow::Result<pageserver::http::models::partitioning::Partitioning> {
+            let uri = Uri::try_from(format!(
+                "{}/v1/tenant/{tenant_id}/timeline/{timeline_id}/keyspace?check_serialization_roundtrip=true",
+                self.mgmt_api_endpoint
+            ))?;
+            let resp = self.client.get(uri).await?;
+            if !resp.status().is_success() {
+                anyhow::bail!("status error");
+            }
+            let body = hyper::body::to_bytes(resp).await?;
+            Ok(serde_json::from_slice(&body).context("deserialize")?)
+        }
+    }
+}
+
+mod getpage_client {
+    use std::pin::Pin;
+
+    use futures::SinkExt;
+    use pageserver_api::models::{
+        PagestreamBeMessage, PagestreamFeMessage, PagestreamGetPageRequest,
+        PagestreamGetPageResponse,
+    };
+    use tokio::task::JoinHandle;
+    use tokio_stream::StreamExt;
+    use tokio_util::sync::CancellationToken;
+    use utils::{
+        id::{TenantId, TimelineId},
+        lsn::Lsn,
+    };
+
+    use crate::RelTagBlockNo;
+
+    pub(crate) struct Client {
+        copy_both: Pin<Box<tokio_postgres::CopyBothDuplex<bytes::Bytes>>>,
+        cancel_on_client_drop: Option<tokio_util::sync::DropGuard>,
+        conn_task: JoinHandle<()>,
+    }
+
+    impl Client {
+        pub async fn new(
+            connstring: String,
+            tenant_id: TenantId,
+            timeline_id: TimelineId,
+        ) -> anyhow::Result<Self> {
+            let (client, connection) =
+                tokio_postgres::connect(&connstring, postgres::NoTls).await?;
+
+            let conn_task_cancel = CancellationToken::new();
+            let conn_task = tokio::spawn({
+                let conn_task_cancel = conn_task_cancel.clone();
+                async move {
+                    tokio::select! {
+                        _ = conn_task_cancel.cancelled() => { }
+                        res = connection => {
+                            res.unwrap();
+                        }
+                    }
+                }
+            });
+
+            let copy_both: tokio_postgres::CopyBothDuplex<bytes::Bytes> = client
+                .copy_both_simple(&format!("pagestream {tenant_id} {timeline_id}"))
+                .await?;
+
+            Ok(Self {
+                copy_both: Box::pin(copy_both),
+                conn_task,
+                cancel_on_client_drop: Some(conn_task_cancel.drop_guard()),
+            })
+        }
+
+        pub async fn shutdown(mut self) {
+            let _ = self.cancel_on_client_drop.take();
+            self.conn_task.await.unwrap();
+        }
+
+        pub async fn getpage(
+            &mut self,
+            key: RelTagBlockNo,
+            lsn: Lsn,
+        ) -> anyhow::Result<PagestreamGetPageResponse> {
+            let req = PagestreamGetPageRequest {
+                latest: false,
+                rel: key.rel_tag,
+                blkno: key.block_no,
+                lsn,
+            };
+            let req = PagestreamFeMessage::GetPage(req);
+            let req: bytes::Bytes = req.serialize();
+            // let mut req = tokio_util::io::ReaderStream::new(&req);
+            let mut req = tokio_stream::once(Ok(req));
+
+            self.copy_both.send_all(&mut req).await?;
+
+            let next: Option<Result<bytes::Bytes, _>> = self.copy_both.next().await;
+            let next = next.unwrap().unwrap();
+
+            match PagestreamBeMessage::deserialize(next)? {
+                PagestreamBeMessage::Exists(_) => todo!(),
+                PagestreamBeMessage::Nblocks(_) => todo!(),
+                PagestreamBeMessage::GetPage(p) => Ok(p),
+                PagestreamBeMessage::Error(e) => anyhow::bail!("Error: {:?}", e),
+                PagestreamBeMessage::DbSize(_) => todo!(),
+            }
+        }
+    }
+}

pageserver/src/consumption_metrics.rs

@@ -261,7 +261,7 @@ async fn calculate_synthetic_size_worker(
             }
         };
 
-        for (tenant_id, tenant_state) in tenants {
+        for (tenant_id, tenant_state, _gen) in tenants {
             if tenant_state != TenantState::Active {
                 continue;
             }

pageserver/src/consumption_metrics/metrics.rs

@@ -197,7 +197,7 @@ pub(super) async fn collect_all_metrics(
         }
     };
 
-    let tenants = futures::stream::iter(tenants).filter_map(|(id, state)| async move {
+    let tenants = futures::stream::iter(tenants).filter_map(|(id, state, _)| async move {
         if state != TenantState::Active {
             None
         } else {

pageserver/src/deletion_queue.rs

@@ -345,7 +345,7 @@ impl DeletionList {
                 result.extend(
                     timeline_layers
                         .into_iter()
-                        .map(|l| timeline_remote_path.join(&Utf8PathBuf::from(l))),
+                        .map(|l| timeline_remote_path.join(Utf8PathBuf::from(l))),
                 );
             }
         }

pageserver/src/disk_usage_eviction_task.rs

@@ -541,7 +541,7 @@ async fn collect_eviction_candidates(
 
     let mut candidates = Vec::new();
 
-    for (tenant_id, _state) in &tenants {
+    for (tenant_id, _state, _gen) in &tenants {
         if cancel.is_cancelled() {
             return Ok(EvictionCandidates::Cancelled);
         }

pageserver/src/http/mod.rs

@@ -1,4 +1,4 @@
 pub mod routes;
 pub use routes::make_router;
 
-pub use pageserver_api::models;
+pub mod models;

pageserver/src/http/models.rs

@@ -0,0 +1,3 @@
+//! If possible, use `::pageserver_api::models` instead.
+
+pub mod partitioning;

pageserver/src/http/models/partitioning.rs

@@ -0,0 +1,112 @@
+use utils::lsn::Lsn;
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct Partitioning {
+    pub keys: crate::keyspace::KeySpace,
+
+    pub at_lsn: Lsn,
+}
+
+impl serde::Serialize for Partitioning {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        pub struct KeySpace<'a>(&'a crate::keyspace::KeySpace);
+
+        impl<'a> serde::Serialize for KeySpace<'a> {
+            fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+            where
+                S: serde::Serializer,
+            {
+                use serde::ser::SerializeSeq;
+                let mut seq = serializer.serialize_seq(Some(self.0.ranges.len()))?;
+                for kr in &self.0.ranges {
+                    seq.serialize_element(&KeyRange(kr))?;
+                }
+                seq.end()
+            }
+        }
+
+        use serde::ser::SerializeMap;
+        let mut map = serializer.serialize_map(Some(2))?;
+        map.serialize_key("keys")?;
+        map.serialize_value(&KeySpace(&self.keys))?;
+        map.serialize_key("at_lsn")?;
+        map.serialize_value(&WithDisplay(&self.at_lsn))?;
+        map.end()
+    }
+}
+
+pub struct WithDisplay<'a, T>(&'a T);
+
+impl<'a, T: std::fmt::Display> serde::Serialize for WithDisplay<'a, T> {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        serializer.collect_str(&self.0)
+    }
+}
+
+pub struct KeyRange<'a>(&'a std::ops::Range<crate::repository::Key>);
+
+impl<'a> serde::Serialize for KeyRange<'a> {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        use serde::ser::SerializeTuple;
+        let mut t = serializer.serialize_tuple(2)?;
+        t.serialize_element(&WithDisplay(&self.0.start))?;
+        t.serialize_element(&WithDisplay(&self.0.end))?;
+        t.end()
+    }
+}
+
+impl<'a> serde::Deserialize<'a> for Partitioning {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'a>,
+    {
+        pub struct KeySpace(crate::keyspace::KeySpace);
+
+        impl<'de> serde::Deserialize<'de> for KeySpace {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: serde::Deserializer<'de>,
+            {
+                #[serde_with::serde_as]
+                #[derive(serde::Deserialize)]
+                #[serde(transparent)]
+                struct Key(#[serde_as(as = "serde_with::DisplayFromStr")] crate::repository::Key);
+
+                #[serde_with::serde_as]
+                #[derive(serde::Deserialize)]
+                struct Range(Key, Key);
+
+                let ranges: Vec<Range> = serde::Deserialize::deserialize(deserializer)?;
+                Ok(Self(crate::keyspace::KeySpace {
+                    ranges: ranges
+                        .into_iter()
+                        .map(|Range(start, end)| (start.0..end.0))
+                        .collect(),
+                }))
+            }
+        }
+
+        #[serde_with::serde_as]
+        #[derive(serde::Deserialize)]
+        struct De {
+            keys: KeySpace,
+            #[serde_as(as = "serde_with::DisplayFromStr")]
+            at_lsn: Lsn,
+        }
+
+        let de: De = serde::Deserialize::deserialize(deserializer)?;
+        Ok(Self {
+            at_lsn: de.at_lsn,
+            keys: de.keys.0,
+        })
+    }
+}

pageserver/src/http/routes.rs

@@ -26,10 +26,6 @@ use utils::http::endpoint::request_span;
 use utils::http::json::json_request_or_empty_body;
 use utils::http::request::{get_request_param, must_get_query_param, parse_query_param};
 
-use super::models::{
-    StatusResponse, TenantConfigRequest, TenantCreateRequest, TenantCreateResponse, TenantInfo,
-    TimelineCreateRequest, TimelineGcRequest, TimelineInfo,
-};
 use crate::context::{DownloadBehavior, RequestContext};
 use crate::deletion_queue::DeletionQueueClient;
 use crate::metrics::{StorageTimeOperation, STORAGE_TIME_GLOBAL};
@@ -46,6 +42,10 @@ use crate::tenant::timeline::Timeline;
 use crate::tenant::{LogicalSizeCalculationCause, PageReconstructError, TenantSharedResources};
 use crate::{config::PageServerConf, tenant::mgr};
 use crate::{disk_usage_eviction_task, tenant};
+use pageserver_api::models::{
+    StatusResponse, TenantConfigRequest, TenantCreateRequest, TenantCreateResponse, TenantInfo,
+    TimelineCreateRequest, TimelineGcRequest, TimelineInfo,
+};
 use utils::{
     auth::SwappableJwtAuth,
     generation::Generation,
@@ -61,7 +61,7 @@ use utils::{
 };
 
 // Imports only used for testing APIs
-use super::models::ConfigureFailpointsRequest;
+use pageserver_api::models::ConfigureFailpointsRequest;
 
 pub struct State {
     conf: &'static PageServerConf,
@@ -764,11 +764,12 @@ async fn tenant_list_handler(
             ApiError::ResourceUnavailable("Tenant map is initializing or shutting down".into())
         })?
         .iter()
-        .map(|(id, state)| TenantInfo {
+        .map(|(id, state, gen)| TenantInfo {
             id: *id,
             state: state.clone(),
             current_physical_size: None,
             attachment_status: state.attachment_status(),
+            generation: (*gen).into(),
         })
         .collect::<Vec<TenantInfo>>();
 
@@ -797,6 +798,7 @@ async fn tenant_status(
             state: state.clone(),
             current_physical_size: Some(current_physical_size),
             attachment_status: state.attachment_status(),
+            generation: tenant.generation().into(),
         })
     }
     .instrument(info_span!("tenant_status_handler", %tenant_id))
@@ -1422,71 +1424,11 @@ async fn timeline_collect_keyspace(
     let timeline_id: TimelineId = parse_request_param(&request, "timeline_id")?;
     check_permission(&request, Some(tenant_id))?;
 
-    struct Partitioning {
-        keys: crate::keyspace::KeySpace,
-
-        at_lsn: Lsn,
-    }
-
-    impl serde::Serialize for Partitioning {
-        fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
-        where
-            S: serde::Serializer,
-        {
-            use serde::ser::SerializeMap;
-            let mut map = serializer.serialize_map(Some(2))?;
-            map.serialize_key("keys")?;
-            map.serialize_value(&KeySpace(&self.keys))?;
-            map.serialize_key("at_lsn")?;
-            map.serialize_value(&WithDisplay(&self.at_lsn))?;
-            map.end()
-        }
-    }
-
-    struct WithDisplay<'a, T>(&'a T);
-
-    impl<'a, T: std::fmt::Display> serde::Serialize for WithDisplay<'a, T> {
-        fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
-        where
-            S: serde::Serializer,
-        {
-            serializer.collect_str(&self.0)
-        }
-    }
-
-    struct KeySpace<'a>(&'a crate::keyspace::KeySpace);
-
-    impl<'a> serde::Serialize for KeySpace<'a> {
-        fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
-        where
-            S: serde::Serializer,
-        {
-            use serde::ser::SerializeSeq;
-            let mut seq = serializer.serialize_seq(Some(self.0.ranges.len()))?;
-            for kr in &self.0.ranges {
-                seq.serialize_element(&KeyRange(kr))?;
-            }
-            seq.end()
-        }
-    }
-
-    struct KeyRange<'a>(&'a std::ops::Range<crate::repository::Key>);
-
-    impl<'a> serde::Serialize for KeyRange<'a> {
-        fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-        where
-            S: serde::Serializer,
-        {
-            use serde::ser::SerializeTuple;
-            let mut t = serializer.serialize_tuple(2)?;
-            t.serialize_element(&WithDisplay(&self.0.start))?;
-            t.serialize_element(&WithDisplay(&self.0.end))?;
-            t.end()
-        }
-    }
-
     let at_lsn: Option<Lsn> = parse_query_param(&request, "at_lsn")?;
 
+    let check_serialization_roundtrip: bool =
+        parse_query_param(&request, "check_serialization_roundtrip")?.unwrap_or(false);
+
     async {
         let ctx = RequestContext::new(TaskKind::MgmtRequest, DownloadBehavior::Download);
         let timeline = active_timeline_of_active_tenant(tenant_id, timeline_id).await?;
@@ -1496,7 +1438,20 @@ async fn timeline_collect_keyspace(
             .await
             .map_err(|e| ApiError::InternalServerError(e.into()))?;
 
-        json_response(StatusCode::OK, Partitioning { keys, at_lsn })
+        let res = crate::http::models::partitioning::Partitioning { keys, at_lsn };
+        if check_serialization_roundtrip {
+            (|| {
+                let ser = serde_json::ser::to_vec(&res).context("serialize")?;
+                let de: crate::http::models::partitioning::Partitioning =
+                    serde_json::from_slice(&ser).context("deserialize")?;
+                anyhow::ensure!(de == res, "not equal");
+                info!("passed serialization rountrip check");
+                Ok(())
+            })()
+            .context("serialization rountrip")
+            .map_err(ApiError::InternalServerError)?;
+        }
+        json_response(StatusCode::OK, res)
     }
     .instrument(info_span!("timeline_collect_keyspace", %tenant_id, %timeline_id))
     .await

pageserver/src/keyspace.rs

@@ -5,7 +5,7 @@ use std::ops::Range;
 ///
 /// Represents a set of Keys, in a compact form.
 ///
-#[derive(Clone, Debug, Default)]
+#[derive(Clone, Debug, Default, PartialEq, Eq)]
 pub struct KeySpace {
     /// Contiguous ranges of keys that belong to the key space. In key order,
     /// and with no overlap.

pageserver/src/pgdatadir_mapping.rs

@@ -1749,6 +1749,7 @@ const AUX_FILES_KEY: Key = Key {
 // Reverse mappings for a few Keys.
 // These are needed by WAL redo manager.
 
+/// Guaranteed to return `Ok()` if [[is_rel_block_key]] returns `true` for `key`.
 pub fn key_to_rel_block(key: Key) -> anyhow::Result<(RelTag, BlockNumber)> {
     Ok(match key.field1 {
         0x00 => (
@@ -1764,7 +1765,8 @@ pub fn key_to_rel_block(key: Key) -> anyhow::Result<(RelTag, BlockNumber)> {
     })
 }
 
-fn is_rel_block_key(key: Key) -> bool {
+/// See [[key_to_rel_block]].
+pub fn is_rel_block_key(key: Key) -> bool {
     key.field1 == 0x00 && key.field4 != 0
 }
 

pageserver/src/tenant.rs

@@ -1715,6 +1715,10 @@ impl Tenant {
         self.current_state() == TenantState::Active
     }
 
+    pub fn generation(&self) -> Generation {
+        self.generation
+    }
+
     /// Changes tenant status to active, unless shutdown was already requested.
     ///
     /// `background_jobs_can_start` is an optional barrier set to a value during pageserver startup

pageserver/src/tenant/mgr.rs

@@ -1397,7 +1397,8 @@ pub(crate) enum TenantMapListError {
 ///
 /// Get list of tenants, for the mgmt API
 ///
-pub(crate) async fn list_tenants() -> Result<Vec<(TenantId, TenantState)>, TenantMapListError> {
+pub(crate) async fn list_tenants(
+) -> Result<Vec<(TenantId, TenantState, Generation)>, TenantMapListError> {
     let tenants = TENANTS.read().unwrap();
     let m = match &*tenants {
         TenantsMap::Initializing => return Err(TenantMapListError::Initializing),
@@ -1405,12 +1406,12 @@ pub(crate) async fn list_tenants() -> Result<Vec<(TenantId, TenantState)>, Tenan
     };
     Ok(m.iter()
         .filter_map(|(id, tenant)| match tenant {
-            TenantSlot::Attached(tenant) => Some((id, tenant.current_state())),
+            TenantSlot::Attached(tenant) => Some((id, tenant.current_state(), tenant.generation())),
             TenantSlot::Secondary => None,
             TenantSlot::InProgress(_) => None,
         })
         // TODO(sharding): make callers of this function shard-aware
-        .map(|(k, v)| (k.tenant_id, v))
+        .map(|(a, b, c)| (a.tenant_id, b, c))
         .collect())
 }
 

pageserver/src/tenant/storage_layer.rs

@@ -2,7 +2,7 @@
 
 pub mod delta_layer;
 mod filename;
-mod image_layer;
+pub mod image_layer;
 mod inmemory_layer;
 mod layer;
 mod layer_desc;

pageserver/src/tenant/storage_layer/delta_layer.rs

@@ -69,13 +69,13 @@ use super::{AsLayerDesc, LayerAccessStats, PersistentLayerDesc, ResidentLayer};
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
 pub struct Summary {
     /// Magic value to identify this as a neon delta file. Always DELTA_FILE_MAGIC.
-    magic: u16,
-    format_version: u16,
+    pub magic: u16,
+    pub format_version: u16,
 
-    tenant_id: TenantId,
-    timeline_id: TimelineId,
-    key_range: Range<Key>,
-    lsn_range: Range<Lsn>,
+    pub tenant_id: TenantId,
+    pub timeline_id: TimelineId,
+    pub key_range: Range<Key>,
+    pub lsn_range: Range<Lsn>,
 
     /// Block number where the 'index' part of the file begins.
     pub index_start_blk: u32,
@@ -611,6 +611,61 @@ impl Drop for DeltaLayerWriter {
     }
 }
 
+#[derive(thiserror::Error, Debug)]
+pub enum RewriteSummaryError {
+    #[error("magic mismatch")]
+    MagicMismatch,
+    #[error(transparent)]
+    Other(#[from] anyhow::Error),
+}
+
+impl From<std::io::Error> for RewriteSummaryError {
+    fn from(e: std::io::Error) -> Self {
+        Self::Other(anyhow::anyhow!(e))
+    }
+}
+
+impl DeltaLayer {
+    pub async fn rewrite_summary<F>(
+        path: &Utf8Path,
+        rewrite: F,
+        ctx: &RequestContext,
+    ) -> Result<(), RewriteSummaryError>
+    where
+        F: Fn(Summary) -> Summary,
+    {
+        let file = VirtualFile::open_with_options(
+            path,
+            &*std::fs::OpenOptions::new().read(true).write(true),
+        )
+        .await
+        .with_context(|| format!("Failed to open file '{}'", path))?;
+        let file = FileBlockReader::new(file);
+        let summary_blk = file.read_blk(0, ctx).await?;
+        let actual_summary = Summary::des_prefix(summary_blk.as_ref()).context("deserialize")?;
+        let mut file = file.file;
+        if actual_summary.magic != DELTA_FILE_MAGIC {
+            return Err(RewriteSummaryError::MagicMismatch);
+        }
+
+        let new_summary = rewrite(actual_summary);
+
+        let mut buf = smallvec::SmallVec::<[u8; PAGE_SZ]>::new();
+        Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
+        if buf.spilled() {
+            // The code in DeltaLayerWriterInner just warn!()s for this.
+            // It should probably error out as well.
+            return Err(RewriteSummaryError::Other(anyhow::anyhow!(
+                "Used more than one page size for summary buffer: {}",
+                buf.len()
+            )));
+        }
+        file.seek(SeekFrom::Start(0)).await?;
+        file.write_all(&buf).await?;
+        Ok(())
+    }
+}
+
 impl DeltaLayerInner {
     /// Returns nested result following Result<Result<_, OpErr>, Critical>:
     /// - inner has the success or transient failure

pageserver/src/tenant/storage_layer/image_layer.rs

@@ -67,20 +67,20 @@ use super::{AsLayerDesc, Layer, PersistentLayerDesc, ResidentLayer};
 /// the 'index' starts at the block indicated by 'index_start_blk'
 ///
 #[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
-pub(super) struct Summary {
+pub struct Summary {
     /// Magic value to identify this as a neon image file. Always IMAGE_FILE_MAGIC.
-    magic: u16,
-    format_version: u16,
+    pub magic: u16,
+    pub format_version: u16,
 
-    tenant_id: TenantId,
-    timeline_id: TimelineId,
-    key_range: Range<Key>,
-    lsn: Lsn,
+    pub tenant_id: TenantId,
+    pub timeline_id: TimelineId,
+    pub key_range: Range<Key>,
+    pub lsn: Lsn,
 
     /// Block number where the 'index' part of the file begins.
-    index_start_blk: u32,
+    pub index_start_blk: u32,
     /// Block within the 'index', where the B-tree root page is stored
-    index_root_blk: u32,
+    pub index_root_blk: u32,
     // the 'values' part starts after the summary header, on block 1.
 }
 
@@ -296,6 +296,61 @@ impl ImageLayer {
     }
 }
 
+#[derive(thiserror::Error, Debug)]
+pub enum RewriteSummaryError {
+    #[error("magic mismatch")]
+    MagicMismatch,
+    #[error(transparent)]
+    Other(#[from] anyhow::Error),
+}
+
+impl From<std::io::Error> for RewriteSummaryError {
+    fn from(e: std::io::Error) -> Self {
+        Self::Other(anyhow::anyhow!(e))
+    }
+}
+
+impl ImageLayer {
+    pub async fn rewrite_summary<F>(
+        path: &Utf8Path,
+        rewrite: F,
+        ctx: &RequestContext,
+    ) -> Result<(), RewriteSummaryError>
+    where
+        F: Fn(Summary) -> Summary,
+    {
+        let file = VirtualFile::open_with_options(
+            path,
+            &*std::fs::OpenOptions::new().read(true).write(true),
+        )
+        .await
+        .with_context(|| format!("Failed to open file '{}'", path))?;
+        let file = FileBlockReader::new(file);
+        let summary_blk = file.read_blk(0, ctx).await?;
+        let actual_summary = Summary::des_prefix(summary_blk.as_ref()).context("deserialize")?;
+        let mut file = file.file;
+        if actual_summary.magic != IMAGE_FILE_MAGIC {
+            return Err(RewriteSummaryError::MagicMismatch);
+        }
+
+        let new_summary = rewrite(actual_summary);
+
+        let mut buf = smallvec::SmallVec::<[u8; PAGE_SZ]>::new();
+        Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
+        if buf.spilled() {
+            // The code in ImageLayerWriterInner just warn!()s for this.
+            // It should probably error out as well.
+            return Err(RewriteSummaryError::Other(anyhow::anyhow!(
+                "Used more than one page size for summary buffer: {}",
+                buf.len()
+            )));
+        }
+        file.seek(SeekFrom::Start(0)).await?;
+        file.write_all(&buf).await?;
+        Ok(())
+    }
+}
+
 impl ImageLayerInner {
     /// Returns nested result following Result<Result<_, OpErr>, Critical>:
     /// - inner has the success or transient failure

pageserver/src/tenant/storage_layer/layer.rs

@@ -3,6 +3,7 @@ use camino::{Utf8Path, Utf8PathBuf};
 use pageserver_api::models::{
     HistoricLayerInfo, LayerAccessKind, LayerResidenceEventReason, LayerResidenceStatus,
 };
+use remote_storage::RemotePath;
 use std::ops::Range;
 use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
 use std::sync::{Arc, Weak};
@@ -305,6 +306,12 @@ impl Layer {
         &self.0.path
     }
 
+    /// This can return None even though it should return Some in some edge cases.
+    #[allow(unused)]
+    pub(crate) fn remote_path(&self) -> Option<RemotePath> {
+        self.0.remote_path()
+    }
+
     pub(crate) fn metadata(&self) -> LayerFileMetadata {
         self.0.metadata()
     }
@@ -918,6 +925,17 @@ impl LayerInner {
         }
     }
 
+    /// This can return None even though it should return Some in some edge cases.
+    fn remote_path(&self) -> Option<RemotePath> {
+        let tl = self.timeline.upgrade()?; // TODO: should distinguish this case, but, accuracy doesn't matter for this field.
+        Some(crate::tenant::remote_timeline_client::remote_layer_path(
+            &tl.tenant_id,
+            &tl.timeline_id,
+            &self.desc.filename(),
+            self.generation,
+        ))
+    }
+
     fn info(&self, reset: LayerAccessStatsReset) -> HistoricLayerInfo {
         let layer_file_name = self.desc.filename().file_name();
 
@@ -937,6 +955,7 @@ impl LayerInner {
                 lsn_end: lsn_range.end,
                 remote,
                 access_stats,
+                remote_path: self.remote_path().map(|p| p.into()),
             }
         } else {
             let lsn = self.desc.image_layer_lsn();
@@ -947,6 +966,7 @@ impl LayerInner {
                 lsn_start: lsn,
                 remote,
                 access_stats,
+                remote_path: self.remote_path().map(|p| p.into()),
             }
         }
     }

test_runner/duplicate_tenant.py

@@ -0,0 +1,69 @@
+# Usage from top of repo:
+#  poetry run python3 ./test_runner/duplicate_tenant.py c66e2e233057f7f05563caff664ecb14 .neon/remote_storage_local_fs
+import argparse
+import shutil
+import subprocess
+import time
+from pathlib import Path
+
+from fixtures.pageserver.http import PageserverHttpClient
+from fixtures.types import TenantId
+
+parser = argparse.ArgumentParser(description="Duplicate tenant script.")
+parser.add_argument("initial_tenant", type=str, help="Initial tenant")
+parser.add_argument("remote_storage_local_fs_root", type=Path, help="Remote storage local fs root")
+parser.add_argument("--ncopies", type=int, help="Number of copies")
+parser.add_argument("--numthreads", type=int, default=1, help="Number of threads")
+parser.add_argument("--port", type=int, default=9898, help="Pageserver management api port")
+
+args = parser.parse_args()
+
+initial_tenant = args.initial_tenant
+remote_storage_local_fs_root: Path = args.remote_storage_local_fs_root
+ncopies = args.ncopies
+numthreads = args.numthreads
+
+new_tenant = TenantId.generate()
+print(f"New tenant: {new_tenant}")
+
+client = PageserverHttpClient(args.port, lambda: None)
+
+src_tenant_gen = int(client.tenant_status(initial_tenant)["generation"])
+
+assert remote_storage_local_fs_root.is_dir(), f"{remote_storage_local_fs_root} is not a directory"
+
+src_timelines_dir: Path = remote_storage_local_fs_root / "tenants" / initial_tenant / "timelines"
+assert src_timelines_dir.is_dir(), f"{src_timelines_dir} is not a directory"
+
+dst_timelines_dir: Path = remote_storage_local_fs_root / "tenants" / str(new_tenant) / "timelines"
+dst_timelines_dir.parent.mkdir(parents=False, exist_ok=False)
+dst_timelines_dir.mkdir(parents=False, exist_ok=False)
+
+for tl in src_timelines_dir.iterdir():
+    src_tl_dir = src_timelines_dir / tl.name
+    assert src_tl_dir.is_dir(), f"{src_tl_dir} is not a directory"
+    dst_tl_dir = dst_timelines_dir / tl.name
+    dst_tl_dir.mkdir(parents=False, exist_ok=False)
+    for file in tl.iterdir():
+        shutil.copy2(file, dst_tl_dir)
+        if "__" in file.name:
+            cmd = [
+                "./target/debug/pagectl",  # TODO: abstract this like the other binaries
+                "layer",
+                "rewrite-summary",
+                str(dst_tl_dir / file.name),
+                "--new-tenant-id",
+                str(new_tenant),
+            ]
+            subprocess.run(cmd, check=True)
+
+client.tenant_attach(new_tenant, generation=src_tenant_gen)
+
+while True:
+    status = client.tenant_status(new_tenant)
+    if status["state"]["slug"] == "Active":
+        break
+    print("Waiting for tenant to be active..., is: " + status["state"]["slug"])
+    time.sleep(1)
+
+print("Tenant is active: " + str(new_tenant))

test_runner/fixtures/neon_fixtures.py

@@ -724,13 +724,10 @@ class NeonEnv:
         self.initial_tenant = config.initial_tenant
         self.initial_timeline = config.initial_timeline
 
+        self.control_plane_api = None
+        self.attachment_service = None
         if config.enable_generations:
-            attachment_service_port = self.port_distributor.get_port()
-            self.control_plane_api: Optional[str] = f"http://127.0.0.1:{attachment_service_port}"
-            self.attachment_service: Optional[NeonAttachmentService] = NeonAttachmentService(self)
-        else:
-            self.control_plane_api = None
-            self.attachment_service = None
+            self.enable_generations()
 
         # Create a config file corresponding to the options
         toml = textwrap.dedent(
@@ -819,6 +816,18 @@ class NeonEnv:
         log.info(f"Config: {toml}")
         self.neon_cli.init(toml)
 
+    def enable_generations(self, start=False):
+        if not start:
+            # TODO: assert that we haven't `self.start()`ed yet
+            pass
+        assert self.control_plane_api == None
+        assert self.attachment_service == None
+        attachment_service_port = self.port_distributor.get_port()
+        self.control_plane_api: Optional[str] = f"http://127.0.0.1:{attachment_service_port}"
+        self.attachment_service: Optional[NeonAttachmentService] = NeonAttachmentService(self)
+        if start:
+            self.attachment_service.start()
+
     def start(self):
         # Start up broker, pageserver and all safekeepers
         self.broker.try_start()

test_runner/fixtures/pageserver/http.py

@@ -58,6 +58,7 @@ class HistoricLayerInfo:
     lsn_start: str
     lsn_end: Optional[str]
     remote: bool
+    remote_path: Optional[str] = None
 
     @classmethod
     def from_json(cls, d: Dict[str, Any]) -> HistoricLayerInfo:
@@ -68,6 +69,7 @@ class HistoricLayerInfo:
             lsn_start=d["lsn_start"],
             lsn_end=d.get("lsn_end"),
             remote=d["remote"],
+            remote_path=d.get("remote_path"),
         )
 
 

test_runner/performance/test_pageserver.py

@@ -0,0 +1,107 @@
+
+from pathlib import Path
+import shutil
+import subprocess
+from fixtures.compare_fixtures import NeonCompare
+from fixtures.remote_storage import LocalFsStorage, RemoteStorageKind
+from fixtures.neon_fixtures import NeonEnvBuilder, PgBin, last_flush_lsn_upload
+from fixtures.pageserver.utils import wait_until_tenant_active
+from fixtures.types import TenantId
+from fixtures.log_helper import log
+from fixtures.benchmark_fixture import NeonBenchmarker
+
+def test_getpage_throughput(neon_env_builder: NeonEnvBuilder, zenbenchmark: NeonBenchmarker, pg_bin: PgBin):
+    neon_env_builder.enable_generations = True
+    neon_env_builder.enable_pageserver_remote_storage(RemoteStorageKind.LOCAL_FS)
+    env = neon_env_builder.init_start()
+
+    remote_storage = env.pageserver_remote_storage
+    assert isinstance(remote_storage, LocalFsStorage)
+
+    ps_http = env.pageserver.http_client()
+
+    # clean up the useless default tenant
+    ps_http.tenant_delete(env.initial_tenant)
+
+    # create our template tenant
+    tenant_config_mgmt_api = {
+        "gc_period" : '0s',
+        "checkpoint_timeout" : '3650 day',
+        "compaction_period" : '20 s',
+        "compaction_threshold" : 10,
+        "compaction_target_size" : 134217728,
+        "checkpoint_distance" : 268435456,
+        "image_creation_threshold" : 3,
+    }
+    tenant_config_cli = { k: str(v) for k, v in tenant_config_mgmt_api.items() }
+
+    template_tenant, template_timeline = env.neon_cli.create_tenant(conf=tenant_config_cli)
+    template_tenant_gen = int(ps_http.tenant_status(template_tenant)["generation"])
+    with env.endpoints.create_start("main", tenant_id=template_tenant) as ep:
+        pg_bin.run_capture(["pgbench", "-i", "-s1", ep.connstr()])
+        last_flush_lsn_upload(env, ep, template_tenant, template_timeline)
+    ps_http.tenant_detach(template_tenant)
+
+    # stop PS just for good measure
+    env.pageserver.stop()
+
+    # duplicate the tenant in remote stora
+    src_timelines_dir: Path = remote_storage.tenant_path(template_tenant) / "timelines"
+    assert src_timelines_dir.is_dir(), f"{src_timelines_dir} is not a directory"
+
+    tenants = [template_tenant]
+
+    for i in range(0, 10):
+        new_tenant = TenantId.generate()
+        tenants.append(new_tenant)
+        log.info("Duplicating tenant #%s: %s", i, new_tenant)
+
+
+        dst_timelines_dir: Path = remote_storage.tenant_path(new_tenant) / "timelines"
+        dst_timelines_dir.parent.mkdir(parents=False, exist_ok=False)
+        dst_timelines_dir.mkdir(parents=False, exist_ok=False)
+
+        for tl in src_timelines_dir.iterdir():
+            src_tl_dir = src_timelines_dir / tl.name
+            assert src_tl_dir.is_dir(), f"{src_tl_dir} is not a directory"
+            dst_tl_dir = dst_timelines_dir / tl.name
+            dst_tl_dir.mkdir(parents=False, exist_ok=False)
+            for file in tl.iterdir():
+                shutil.copy2(file, dst_tl_dir)
+                if "__" in file.name:
+                    cmd = [
+                        env.neon_binpath / "pagectl",  # TODO: abstract this like the other binaries
+                        "layer",
+                        "rewrite-summary",
+                        str(dst_tl_dir / file.name),
+                        "--new-tenant-id",
+                        str(new_tenant),
+                    ]
+                    subprocess.run(cmd, check=True)
+                else:
+                    # index_part etc need no patching
+                    pass
+
+    env.pageserver.start()
+    assert ps_http.tenant_list() == []
+    for tenant in tenants:
+        ps_http.tenant_attach(tenant, config=tenant_config_mgmt_api, generation=template_tenant_gen+1)
+    for tenant in tenants:
+        wait_until_tenant_active(ps_http, tenant)
+
+    # ensure all layers are resident for predictiable performance
+    # TODO: ensure all kinds of eviction are disabled (per-tenant, disk-usage-based)
+    for tenant in tenants:
+        ps_http.download_all_layers(tenant, template_timeline)
+
+    # run the benchmark
+    cmd = [
+        str(env.neon_binpath / "getpage_bench_libpq"),
+        "--mgmt-api-endpoint", ps_http.base_url,
+        "--page-service-connstring", env.pageserver.connstr(password=None),
+        "--num-tasks", "1",
+        "--num-requests", "10000",
+        *[str(tenant) for tenant in tenants],
+    ]
+    basepath = pg_bin.run_capture(cmd)
+    log.info("Benchmark results: %s", basepath + ".stdout")