On Fri, 2013-06-21 at 17:25 -0700, Michel Lespinasse wrote: > On Fri, Jun 21, 2013 at 5:00 PM, Davidlohr Bueso <davidlohr.bueso@xxxxxx> wrote: > > On Fri, 2013-06-21 at 16:51 -0700, Tim Chen wrote: > >> 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. > > > > Tim, I was really hoping to send all this in one big bundle. I was doing > > some further testing (enabling hyperthreading and some Oracle runs), > > fortunately everything looks ok and we are getting actual improvements > > on large boxes. > > > > That said, how about I send you my i_mmap rwsem patchset for a v2 of > > this patchset? > > I'm a bit confused about the state of these patchsets - it looks like > I'm only copied into half of the conversations. Should I wait for a v2 > here, or should I hunt down for Alex's version of things, or... ? Except for some internal patch logistics, you haven't been left out on any conversations :) My original plan was to send out, in one patchset: - rwsem optimizations from Alex (patch 1/2 here, which should be actually 4 patches) + - rwsem optimistic spinning (patch 2/2 here) + - i_mmap_mutex to rwsem conversion (5 more patches) Now, I realize that the i_mmap stuff might not be welcomed in a rwsem-specific optimizations patchset like this one, but I think it's relevant to include everything in a single bundle as it really shows the performance boosts and it's what I have been using and measuring the original negative rwsem performance when compared to a mutex. If folks don't agree, I can always send it as a separate patchset. Thanks, Davidlohr the rwsem spin on owner functionality (2/2) + 4 from Alex )which is really patch 1/2 here + I haven't sent out any -- 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>