lkml.org 
[lkml]   [2013]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Subject[PATCH 0/2] rwsem: performance enhancements for systems with many cores
From
Date
In this patchset, we introduce two optimizations to read write semaphore.
The first one reduces cache bouncing of the sem->count field
by doing a pre-read of the sem->count and avoid cmpxchg if possible.
The second patch introduces similar optimistic spining logic in
the mutex code for the writer lock acquisition of rw-sem.

Combining the two patches, in testing by Davidlohr Bueso on aim7 workloads
on 8 socket 80 cores system, he saw improvements of
alltests (+14.5%), custom (+17%), disk (+11%), high_systime
(+5%), shared (+15%) and short (+4%), most of them after around 500
users when i_mmap was implemented as rwsem.

Feedbacks on the effectiveness of these tweaks on other workloads
will be appreciated.


Alex Shi (1):
rwsem: check the lock before cpmxchg in down_write_trylock and
rwsem_do_wake

Tim Chen (1):
rwsem: do optimistic spinning for writer lock acquisition

Makefile | 2 +-
include/asm-generic/rwsem.h | 8 +-
include/linux/rwsem.h | 3 +
init/Kconfig | 9 +++
kernel/rwsem.c | 29 +++++++-
lib/rwsem.c | 169 ++++++++++++++++++++++++++++++++++++++-----
6 files changed, 195 insertions(+), 25 deletions(-)

--
1.7.4.4




\
 
 \ /
  Last update: 2013-06-22 02:01    [W:0.051 / U:0.084 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site