Revert "investigation: add log_if_slow => shows that the io_futures are slow"

This reverts commit e81fa7137e.

pageserver/src/lib.rs

@@ -375,48 +375,6 @@ async fn timed_after_cancellation<Fut: std::future::Future>(
     }
 }
 
-async fn log_if_slow<Fut: std::future::Future>(
-    name: &str,
-    warn_after: std::time::Duration,
-    fut: Fut,
-) -> <Fut as std::future::Future>::Output {
-    let started = std::time::Instant::now();
-
-    let mut fut = std::pin::pin!(fut);
-
-    match tokio::time::timeout(warn_after, &mut fut).await {
-        Ok(ret) => ret,
-        Err(_) => {
-            tracing::info!(
-                what = name,
-                elapsed_ms = started.elapsed().as_millis(),
-                "slow future"
-            );
-
-            let res = fut.await;
-
-            tracing::info!(
-                what = name,
-                elapsed_ms = started.elapsed().as_millis(),
-                "slow future completed"
-            );
-
-            res
-        }
-    }
-}
-
-pub(crate) trait LogIfSlowFutureExt: std::future::Future {
-    async fn log_if_slow(self, name: &'static str, warn_after: std::time::Duration) -> Self::Output
-    where
-        Self: Sized,
-    {
-        log_if_slow(name, warn_after, self).await
-    }
-}
-
-impl<Fut> LogIfSlowFutureExt for Fut where Fut: std::future::Future {}
-
 #[cfg(test)]
 mod timed_tests {
     use super::timed;

pageserver/src/tenant/storage_layer.rs

@@ -10,8 +10,6 @@ mod layer_desc;
 mod layer_name;
 pub mod merge_iterator;
 
-use crate::LogIfSlowFutureExt;
-
 use crate::context::{AccessStatsBehavior, RequestContext};
 use bytes::Bytes;
 use futures::stream::FuturesUnordered;
@@ -350,7 +348,7 @@ impl IoConcurrency {
         match self {
             IoConcurrency::Serial => fut.await,
             IoConcurrency::FuturesUnordered { ios_tx, .. } => {
-                let fut = Box::pin(fut.log_if_slow("spawned_io", Duration::from_secs(1)));
+                let fut = Box::pin(fut);
                 // NB: experiments showed that doing an opportunistic poll of `fut` here was bad for throughput
                 // while insignificant for latency.
                 // It would make sense to revisit the tokio-epoll-uring API in the future such that we can try