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 ;-) -- 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>