From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f176.google.com (mail-wi0-f176.google.com [209.85.212.176]) by kanga.kvack.org (Postfix) with ESMTP id 92D2B6B0032 for ; Wed, 10 Jun 2015 04:33:38 -0400 (EDT) Received: by wifx6 with SMTP id x6so39372255wif.0 for ; Wed, 10 Jun 2015 01:33:38 -0700 (PDT) Received: from mail-wg0-x22f.google.com (mail-wg0-x22f.google.com. [2a00:1450:400c:c00::22f]) by mx.google.com with ESMTPS id go2si8228929wib.16.2015.06.10.01.33.36 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 10 Jun 2015 01:33:37 -0700 (PDT) Received: by wgv5 with SMTP id 5so29952032wgv.1 for ; Wed, 10 Jun 2015 01:33:36 -0700 (PDT) Date: Wed, 10 Jun 2015 10:33:32 +0200 From: Ingo Molnar Subject: Re: [PATCH 2/4] mm: Send one IPI per CPU to TLB flush all entries after unmapping pages Message-ID: <20150610083332.GA25605@gmail.com> References: <1433871118-15207-1-git-send-email-mgorman@suse.de> <1433871118-15207-3-git-send-email-mgorman@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1433871118-15207-3-git-send-email-mgorman@suse.de> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Andrew Morton , Rik van Riel , Hugh Dickins , Minchan Kim , Dave Hansen , Andi Kleen , H Peter Anvin , Linus Torvalds , Thomas Gleixner , Peter Zijlstra , Linux-MM , LKML * Mel Gorman wrote: > Linear mapped reader on a 4-node machine with 64G RAM and 48 CPUs > > 4.1.0-rc6 4.1.0-rc6 > vanilla flushfull-v6 > Ops lru-file-mmap-read-elapsed 162.88 ( 0.00%) 120.81 ( 25.83%) > > 4.1.0-rc6 4.1.0-rc6 > vanillaflushfull-v6r5 > User 568.96 614.68 > System 6085.61 4226.61 > Elapsed 164.24 122.17 > > This is showing that the readers completed 25.83% faster with 30% less > system CPU time. From vmstats, it is known that the vanilla kernel was > interrupted roughly 900K times per second during the steady phase of the > test and the patched kernel was interrupts 180K times per second. > > The impact is lower on a single socket machine. > > 4.1.0-rc6 4.1.0-rc6 > vanilla flushfull-v6 > Ops lru-file-mmap-read-elapsed 25.43 ( 0.00%) 20.59 ( 19.03%) > > 4.1.0-rc6 4.1.0-rc6 > vanilla flushfull-v6 > User 59.14 58.99 > System 109.15 77.84 > Elapsed 27.32 22.31 > > It's still a noticeable improvement with vmstat showing interrupts went > from roughly 500K per second to 45K per second. Btw., I tried to compare your previous (v5) pfn-tracking numbers with these full-flushing numbers, and found that the IRQ rate appears to be the same: > > From vmstats, it is known that the vanilla kernel was interrupted roughly 900K > > times per second during the steady phase of the test and the patched kernel > > was interrupts 180K times per second. > > It's still a noticeable improvement with vmstat showing interrupts went from > > roughly 500K per second to 45K per second. ... is that because the batching limit in the pfn-tracking case was high enough to not be noticeable in the vmstat? In the full-flushing case (v6 without patch 4) the batching limit is 'infinite', we'll batch as long as possible, right? Or have I managed to get confused somewhere ... Thanks, Ingo -- 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