From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) (using TLSv1 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 752C41A2A85 for ; Fri, 20 Mar 2015 21:12:56 +1100 (AEDT) Date: Fri, 20 Mar 2015 10:12:46 +0000 From: Mel Gorman To: Linus Torvalds Subject: Re: [PATCH 4/4] mm: numa: Slow PTE scan rate if migration failures occur Message-ID: <20150320101246.GF3087@suse.de> References: <20150317205104.GA28621@dastard> <20150317220840.GC28621@dastard> <20150319224143.GI10105@dastard> <20150320002311.GG28621@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 In-Reply-To: Cc: Dave Chinner , Linux Kernel Mailing List , xfs@oss.sgi.com, Linux-MM , Aneesh Kumar , Andrew Morton , ppc-dev , Ingo Molnar List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Mar 19, 2015 at 06:29:47PM -0700, Linus Torvalds wrote: > 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). > As a side-note, I did test a patch that checked pte_write and preserved it across both faults and setting the protections. It did not alter migration activity much but there was a drop in minor faults - 20% drop in autonumabench, 58% drop in xfsrepair workload. I'm assuming this is due to refaults to mark pages writable. The patch looks and is hacky so I won't post it to save people bleaching their eyes. I'll spend some time soon (hopefully today) at a smooth way of falling through to WP checks after trapping a NUMA fault. -- Mel Gorman SUSE Labs