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| author | Sebastian Andrzej Siewior <[email protected]> | 2025-06-30 14:50:34 +0000 |
|---|---|---|
| committer | Peter Zijlstra <[email protected]> | 2025-07-01 13:02:05 +0000 |
| commit | 9a57c3773152a3ff2c35cc8325e088d011c9f83b (patch) | |
| tree | 8d8142ce34bc9355fe9aab42e4179390df261e53 /drivers/pci/controller/pci-host-common.c | |
| parent | Linux 6.16-rc4 (diff) | |
| download | kernel-9a57c3773152a3ff2c35cc8325e088d011c9f83b.tar.gz kernel-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/[email protected]/
Reported-by: Chris Mason <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Diffstat (limited to 'drivers/pci/controller/pci-host-common.c')
0 files changed, 0 insertions, 0 deletions