jemalloc: Enable background thread to reduce tail latency (#16780) (#…

…17007)

ref #15927

Per jemalloc tuning guide, enable background thread of jemalloc to improve tail latency

Signed-off-by: ti-chi-bot <[email protected]>

Co-authored-by: Connor <[email protected]>

components/tikv_alloc/src/jemalloc.rs

@@ -342,6 +342,7 @@ mod profiling {
  const OPT_PROF: &[u8] = b"opt.prof\0";
  const ARENAS_CREATE: &[u8] = b"arenas.create\0";
  const THREAD_ARENA: &[u8] = b"thread.arena\0";
+ const BACKGROUND_THREAD: &[u8] = b"background_thread\0";
 
  pub fn set_thread_exclusive_arena(enable: bool) {
  ENABLE_THREAD_EXCLUSIVE_ARENA.store(enable, Ordering::Relaxed);
@@ -387,6 +388,18 @@ mod profiling {
  Ok(())
  }
 
+ fn enable_background_thread() -> ProfResult<()> {
+ unsafe {
+ if let Err(e) = tikv_jemalloc_ctl::raw::write(BACKGROUND_THREAD, true) {
+ return Err(ProfError::JemallocError(format!(
+ "failed to enable background thread: {}",
+ e
+ )));
+ }
+ }
+ Ok(())
+ }
+
  pub fn fetch_arena_stats(index: usize) -> (u64, u64, u64) {
  let resident = unsafe {
  tikv_jemalloc_ctl::raw::read(format!("stats.arenas.{}.resident\0", index).as_bytes())
@@ -434,6 +447,7 @@ mod profiling {
  )));
  }
  }
+ enable_background_thread()?;
  Ok(())
  }