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page cache: add size metrics (#4629)

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Make them a member of `struct PageCache` to prepare for a future
where there's no global state.
This commit is contained in:
Christian Schwarz
2023-07-05 14:36:42 +02:00
committed by GitHub
parent 1c516906e7
commit 505aa242ac
3 changed files with 91 additions and 4 deletions
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49
pageserver/src/metrics.rs
View File

@@ -1,9 +1,9 @@
use metrics::metric_vec_duration::DurationResultObserver;
use metrics::{
register_counter_vec, register_histogram, register_histogram_vec, register_int_counter,
register_int_counter_vec, register_int_gauge, register_int_gauge_vec, register_uint_gauge_vec,
Counter, CounterVec, Histogram, HistogramVec, IntCounter, IntCounterVec, IntGauge, IntGaugeVec,
UIntGauge, UIntGaugeVec,
register_int_counter_vec, register_int_gauge, register_int_gauge_vec, register_uint_gauge,
register_uint_gauge_vec, Counter, CounterVec, Histogram, HistogramVec, IntCounter,
IntCounterVec, IntGauge, IntGaugeVec, UIntGauge, UIntGaugeVec,
};
use once_cell::sync::Lazy;
use pageserver_api::models::TenantState;
@@ -203,6 +203,49 @@ pub static PAGE_CACHE: Lazy<PageCacheMetrics> = Lazy::new(|| PageCacheMetrics {
},
});
pub struct PageCacheSizeMetrics {
pub max_bytes: UIntGauge,
pub current_bytes_ephemeral: UIntGauge,
pub current_bytes_immutable: UIntGauge,
pub current_bytes_materialized_page: UIntGauge,
}
static PAGE_CACHE_SIZE_CURRENT_BYTES: Lazy<UIntGaugeVec> = Lazy::new(|| {
register_uint_gauge_vec!(
"pageserver_page_cache_size_current_bytes",
"Current size of the page cache in bytes, by key kind",
&["key_kind"]
)
.expect("failed to define a metric")
});
pub static PAGE_CACHE_SIZE: Lazy<PageCacheSizeMetrics> = Lazy::new(|| PageCacheSizeMetrics {
max_bytes: {
register_uint_gauge!(
"pageserver_page_cache_size_max_bytes",
"Maximum size of the page cache in bytes"
)
.expect("failed to define a metric")
},
current_bytes_ephemeral: {
PAGE_CACHE_SIZE_CURRENT_BYTES
.get_metric_with_label_values(&["ephemeral"])
.unwrap()
},
current_bytes_immutable: {
PAGE_CACHE_SIZE_CURRENT_BYTES
.get_metric_with_label_values(&["immutable"])
.unwrap()
},
current_bytes_materialized_page: {
PAGE_CACHE_SIZE_CURRENT_BYTES
.get_metric_with_label_values(&["materialized_page"])
.unwrap()
},
});
static WAIT_LSN_TIME: Lazy<HistogramVec> = Lazy::new(|| {
register_histogram_vec!(
"pageserver_wait_lsn_seconds",

44
pageserver/src/page_cache.rs
View File

@@ -53,8 +53,8 @@ use utils::{
lsn::Lsn,
};
use crate::repository::Key;
use crate::tenant::writeback_ephemeral_file;
use crate::{metrics::PageCacheSizeMetrics, repository::Key};
static PAGE_CACHE: OnceCell<PageCache> = OnceCell::new();
const TEST_PAGE_CACHE_SIZE: usize = 50;
@@ -187,6 +187,8 @@ pub struct PageCache {
/// Index of the next candidate to evict, for the Clock replacement algorithm.
/// This is interpreted modulo the page cache size.
next_evict_slot: AtomicUsize,
size_metrics: &'static PageCacheSizeMetrics,
}
///
@@ -718,6 +720,9 @@ impl PageCache {
if let Ok(version_idx) = versions.binary_search_by_key(old_lsn, |v| v.lsn) {
versions.remove(version_idx);
self.size_metrics
.current_bytes_materialized_page
.sub_page_sz(1);
if versions.is_empty() {
old_entry.remove_entry();
}
@@ -730,11 +735,13 @@ impl PageCache {
let mut map = self.ephemeral_page_map.write().unwrap();
map.remove(&(*file_id, *blkno))
.expect("could not find old key in mapping");
self.size_metrics.current_bytes_ephemeral.sub_page_sz(1);
}
CacheKey::ImmutableFilePage { file_id, blkno } => {
let mut map = self.immutable_page_map.write().unwrap();
map.remove(&(*file_id, *blkno))
.expect("could not find old key in mapping");
self.size_metrics.current_bytes_immutable.sub_page_sz(1);
}
}
}
@@ -762,6 +769,9 @@ impl PageCache {
slot_idx,
},
);
self.size_metrics
.current_bytes_materialized_page
.add_page_sz(1);
None
}
}
@@ -772,6 +782,7 @@ impl PageCache {
Entry::Occupied(entry) => Some(*entry.get()),
Entry::Vacant(entry) => {
entry.insert(slot_idx);
self.size_metrics.current_bytes_ephemeral.add_page_sz(1);
None
}
}
@@ -782,6 +793,7 @@ impl PageCache {
Entry::Occupied(entry) => Some(*entry.get()),
Entry::Vacant(entry) => {
entry.insert(slot_idx);
self.size_metrics.current_bytes_immutable.add_page_sz(1);
None
}
}
@@ -881,6 +893,12 @@ impl PageCache {
let page_buffer = Box::leak(vec![0u8; num_pages * PAGE_SZ].into_boxed_slice());
let size_metrics = &crate::metrics::PAGE_CACHE_SIZE;
size_metrics.max_bytes.set_page_sz(num_pages);
size_metrics.current_bytes_ephemeral.set_page_sz(0);
size_metrics.current_bytes_immutable.set_page_sz(0);
size_metrics.current_bytes_materialized_page.set_page_sz(0);
let slots = page_buffer
.chunks_exact_mut(PAGE_SZ)
.map(|chunk| {
@@ -903,6 +921,30 @@ impl PageCache {
immutable_page_map: Default::default(),
slots,
next_evict_slot: AtomicUsize::new(0),
size_metrics,
}
}
}
trait PageSzBytesMetric {
fn set_page_sz(&self, count: usize);
fn add_page_sz(&self, count: usize);
fn sub_page_sz(&self, count: usize);
}
#[inline(always)]
fn count_times_page_sz(count: usize) -> u64 {
u64::try_from(count).unwrap() * u64::try_from(PAGE_SZ).unwrap()
}
impl PageSzBytesMetric for metrics::UIntGauge {
fn set_page_sz(&self, count: usize) {
self.set(count_times_page_sz(count));
}
fn add_page_sz(&self, count: usize) {
self.add(count_times_page_sz(count));
}
fn sub_page_sz(&self, count: usize) {
self.sub(count_times_page_sz(count));
}
}

2
test_runner/fixtures/metrics.py
View File

@@ -61,6 +61,8 @@ PAGESERVER_GLOBAL_METRICS: Tuple[str, ...] = (
"pageserver_materialized_cache_hits_direct_total",
"pageserver_page_cache_read_hits_total",
"pageserver_page_cache_read_accesses_total",
"pageserver_page_cache_size_current_bytes",
"pageserver_page_cache_size_max_bytes",
"pageserver_getpage_reconstruct_seconds_bucket",
"pageserver_getpage_reconstruct_seconds_count",
"pageserver_getpage_reconstruct_seconds_sum",