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| author | Edward Tomasz Napierala <trasz@FreeBSD.org> | 2021-02-25 18:48:50 +0000 |
|---|---|---|
| committer | Edward Tomasz Napierala <trasz@FreeBSD.org> | 2021-02-25 18:55:26 +0000 |
| commit | e7a5b3bd058975ff3ffa346664690e54c641fc0f (patch) | |
| tree | 0ff9bceb8c07f8b9e7fa6a7d1fc80879a586308d | |
| parent | 22267215d66d9bd490ad1a12221472028e3174f4 (diff) | |
| download | src-e7a5b3bd058975ff3ffa346664690e54c641fc0f.tar.gz src-e7a5b3bd058975ff3ffa346664690e54c641fc0f.zip | |
Modify lock_delay() to increase the delay time after spinning
Modify lock_delay() to increase the delay time after spinning,
not before. Previously we would spin at least twice instead of once.
In NetApp's benchmarks this fixes a performance regression compared
to FreeBSD 10, which called cpu_spinwait() directly.
Reviewed By: mjg
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D27331
| -rw-r--r-- | sys/kern/subr_lock.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/sys/kern/subr_lock.c b/sys/kern/subr_lock.c index a74f7e62db4a..8b08c61715b3 100644 --- a/sys/kern/subr_lock.c +++ b/sys/kern/subr_lock.c @@ -128,10 +128,6 @@ lock_delay(struct lock_delay_arg *la) struct lock_delay_config *lc = la->config; u_short i; - la->delay <<= 1; - if (__predict_false(la->delay > lc->max)) - la->delay = lc->max; - for (i = la->delay; i > 0; i--) cpu_spinwait(); @@ -141,6 +137,10 @@ lock_delay(struct lock_delay_arg *la) if (restrict_starvation) la->delay = lc->base; } + + la->delay <<= 1; + if (__predict_false(la->delay > lc->max)) + la->delay = lc->max; } static u_int |