diff options
| author | Waiman Long <longman@redhat.com> | 2019-05-20 16:59:11 -0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-06-17 12:28:05 +0200 |
| commit | cf69482d62d996d3ce840eeead8e160de281ac6c (patch) | |
| tree | 14a8c566cc5db82949ebf95c068cd8248a606f13 /kernel/locking/lock_events_list.h | |
| parent | 02f1082b003a0cd48f48f12533d969cdbf1c2b63 (diff) | |
locking/rwsem: Enable readers spinning on writer
This patch enables readers to optimistically spin on a
rwsem when it is owned by a writer instead of going to sleep
directly. The rwsem_can_spin_on_owner() function is extracted
out of rwsem_optimistic_spin() and is called directly by
rwsem_down_read_slowpath() and rwsem_down_write_slowpath().
With a locking microbenchmark running on 5.1 based kernel, the total
locking rates (in kops/s) on a 8-socket IvyBrige-EX system with equal
numbers of readers and writers before and after the patch were as
follows:
# of Threads Pre-patch Post-patch
------------ --------- ----------
4 1,674 1,684
8 1,062 1,074
16 924 900
32 300 458
64 195 208
128 164 168
240 149 143
The performance change wasn't significant in this case, but this change
is required by a follow-on patch.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: huang ying <huang.ying.caritas@gmail.com>
Link: https://lkml.kernel.org/r/20190520205918.22251-13-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/locking/lock_events_list.h')
| -rw-r--r-- | kernel/locking/lock_events_list.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/locking/lock_events_list.h b/kernel/locking/lock_events_list.h index 634b47fd8b5e..ca954e4e00e4 100644 --- a/kernel/locking/lock_events_list.h +++ b/kernel/locking/lock_events_list.h @@ -56,6 +56,7 @@ LOCK_EVENT(rwsem_sleep_reader) /* # of reader sleeps */ LOCK_EVENT(rwsem_sleep_writer) /* # of writer sleeps */ LOCK_EVENT(rwsem_wake_reader) /* # of reader wakeups */ LOCK_EVENT(rwsem_wake_writer) /* # of writer wakeups */ +LOCK_EVENT(rwsem_opt_rlock) /* # of read locks opt-spin acquired */ LOCK_EVENT(rwsem_opt_wlock) /* # of write locks opt-spin acquired */ LOCK_EVENT(rwsem_opt_fail) /* # of failed opt-spinnings */ LOCK_EVENT(rwsem_rlock) /* # of read locks acquired */ |