On Mon, 2013-06-24 at 10:46 +0200, Peter Zijlstra wrote: > On Fri, Jun 21, 2013 at 04:51:40PM -0700, Tim Chen wrote: > > Introduce in this patch optimistic spinning for writer lock > > acquisition in read write semaphore. The logic is > > similar to the optimistic spinning in mutex but without > > the MCS lock queueing of the spinner. This provides a > > better chance for a writer to acquire the lock before > > being we block it and put it to sleep. > > > > Disabling of pre-emption during optimistic spinning > > was suggested by Davidlohr Bueso. It > > improved performance of aim7 for his test suite. > > > > Combined with the patch to avoid unnecesary cmpxchg, > > 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 he implemented i_mmap as rwsem. > > > > Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx> > > --- > > Makefile | 2 +- > > include/linux/rwsem.h | 3 + > > init/Kconfig | 9 +++ > > kernel/rwsem.c | 29 +++++++++- > > lib/rwsem.c | 148 +++++++++++++++++++++++++++++++++++++++++++++---- > > 5 files changed, 178 insertions(+), 13 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index 49aa84b..7d1ef64 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -1,7 +1,7 @@ > > VERSION = 3 > > PATCHLEVEL = 10 > > SUBLEVEL = 0 > > -EXTRAVERSION = -rc4 > > +EXTRAVERSION = -rc4-optspin4 > > NAME = Unicycling Gorilla > > > > # *DOCUMENTATION* > > I'm fairly sure we don't want to commit this hunk ;-) Fat fingers. Thanks for catching. Tim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>