diff options
| author |   Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2025-06-30 16:50:34 +0200 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2025-07-01 15:02:05 +0200 |
| commit | 9a57c3773152a3ff2c35cc8325e088d011c9f83b (patch) | |
| tree | 8d8142ce34bc9355fe9aab42e4179390df261e53 /rust/pin-init/internal/src | |
| parent | Linux 6.16-rc4 (diff) | |
| download | wireguard-linux-9a57c3773152a3ff2c35cc8325e088d011c9f83b.tar.xz wireguard-linux-9a57c3773152a3ff2c35cc8325e088d011c9f83b.zip | |
futex: Temporary disable FUTEX_PRIVATE_HASH
Chris Mason reported a performance regression on big iron. Reports of
this kind were usually reported as part of a micro benchmark but Chris'
test did mimic his real workload. This makes it a real regression.
The root cause is rcuref_get() which is invoked during each futex
operation. If all threads of an application do this simultaneously then
it leads to cache line bouncing and the performance drops.
Disable FUTEX_PRIVATE_HASH entirely for this cycle. The performance
regression will be addressed in the following cycle enabling the option
again.
Closes: https://lore.kernel.org/all/3ad05298-351e-4d61-9972-ca45a0a50e33@meta.com/
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250630145034.8JnINEaS@linutronix.de
Diffstat (limited to 'rust/pin-init/internal/src')
0 files changed, 0 insertions, 0 deletions