From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx182.postini.com [74.125.245.182]) by kanga.kvack.org (Postfix) with SMTP id D51116B0031 for ; Fri, 21 Jun 2013 20:25:21 -0400 (EDT) Received: by mail-ie0-f175.google.com with SMTP id a13so20512351iee.20 for ; Fri, 21 Jun 2013 17:25:16 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <1371859222.13136.11.camel@buesod1.americas.hpqcorp.net> References: <1371858691.22432.3.camel@schen9-DESK> <1371859222.13136.11.camel@buesod1.americas.hpqcorp.net> Date: Fri, 21 Jun 2013 17:25:16 -0700 Message-ID: Subject: Re: [PATCH 0/2] rwsem: performance enhancements for systems with many cores From: Michel Lespinasse Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Davidlohr Bueso Cc: Tim Chen , Ingo Molnar , Andrew Morton , Andrea Arcangeli , Alex Shi , Andi Kleen , Matthew R Wilcox , Dave Hansen , Peter Zijlstra , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm On Fri, Jun 21, 2013 at 5:00 PM, Davidlohr Bueso 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... ? -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org