From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 1D3317F37 for ; Thu, 19 Mar 2015 23:14:15 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay3.corp.sgi.com (Postfix) with ESMTP id 75D2DAC005 for ; Thu, 19 Mar 2015 21:14:14 -0700 (PDT) Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id Ls7gNC6G3DpHn9c2 for ; Thu, 19 Mar 2015 21:14:10 -0700 (PDT) Date: Fri, 20 Mar 2015 15:13:57 +1100 From: Dave Chinner Subject: Re: [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur Message-ID: <20150320041357.GO10105@dastard> References: <20150317205104.GA28621@dastard> <20150317220840.GC28621@dastard> <20150319224143.GI10105@dastard> <20150320002311.GG28621@dastard> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Linus Torvalds Cc: Linux Kernel Mailing List , xfs@oss.sgi.com, Linux-MM , Aneesh Kumar , Andrew Morton , ppc-dev , Ingo Molnar , Mel Gorman On Thu, Mar 19, 2015 at 06:29:47PM -0700, Linus Torvalds wrote: > On Thu, Mar 19, 2015 at 5:23 PM, Dave Chinner wrote: > > > > Bit more variance there than the pte checking, but runtime > > difference is in the noise - 5m4s vs 4m54s - and profiles are > > identical to the pte checking version. > > Ahh, so that "!(vma->vm_flags & VM_WRITE)" test works _almost_ as well > as the original !pte_write() test. > > Now, can you check that on top of rc4? If I've gotten everything > right, we now have: > > - plain 3.19 (pte_write): 4m54s > - 3.19 with vm_flags & VM_WRITE: 5m4s > - 3.19 with pte_dirty: 5m20s *nod* > so the pte_dirty version seems to have been a bad choice indeed. > > For 4.0-rc4, (which uses pte_dirty) you had 7m50s, so it's still > _much_ worse, but I'm wondering whether that VM_WRITE test will at > least shrink the difference like it does for 3.19. Testing now. It's a bit faster - three runs gave 7m35s, 7m20s and 7m36s. IOWs's a bit better, but not significantly. page migrations are pretty much unchanged, too: 558,632 migrate:mm_migrate_pages ( +- 6.38% ) > And the VM_WRITE test should be stable and not have any subtle > interaction with the other changes that the numa pte things > introduced. It would be good to see if the profiles then pop something > *else* up as the performance difference (which I'm sure will remain, > since the 7m50s was so far off). No, nothing new pops up in the kernel profiles. All the system CPU time is still being spent sending IPIs on the tlb flush path. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs