From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt0-f200.google.com (mail-qt0-f200.google.com [209.85.216.200]) by kanga.kvack.org (Postfix) with ESMTP id 24BFF6B0253 for ; Fri, 27 Oct 2017 16:30:19 -0400 (EDT) Received: by mail-qt0-f200.google.com with SMTP id k31so5407252qta.22 for ; Fri, 27 Oct 2017 13:30:19 -0700 (PDT) Received: from rcdn-iport-3.cisco.com (rcdn-iport-3.cisco.com. [173.37.86.74]) by mx.google.com with ESMTPS id c16si4017360qkj.104.2017.10.27.13.30.17 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 27 Oct 2017 13:30:18 -0700 (PDT) Subject: Re: Detecting page cache trashing state References: <150543458765.3781.10192373650821598320@takondra-t460s> <20170915143619.2ifgex2jxck2xt5u@dhcp22.suse.cz> <150549651001.4512.15084374619358055097@takondra-t460s> <20170918163434.GA11236@cmpxchg.org> From: "Ruslan Ruslichenko -X (rruslich - GLOBALLOGIC INC at Cisco)" Message-ID: Date: Fri, 27 Oct 2017 23:29:55 +0300 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: vinayak menon Cc: Johannes Weiner , Taras Kondratiuk , Michal Hocko , "linux-mm@kvack.org" , xe-linux-external@cisco.com, linux-kernel@vger.kernel.org On 10/26/2017 06:53 AM, vinayak menon wrote: > On Thu, Sep 28, 2017 at 9:19 PM, Ruslan Ruslichenko -X (rruslich - > GLOBALLOGIC INC at Cisco) wrote: >> Hi Johannes, >> >> Hopefully I was able to rebase the patch on top v4.9.26 (latest supported >> version by us right now) >> and test a bit. >> The overall idea definitely looks promising, although I have one question on >> usage. >> Will it be able to account the time which processes spend on handling major >> page faults >> (including fs and iowait time) of refaulting page? >> >> As we have one big application which code space occupies big amount of place >> in page cache, >> when the system under heavy memory usage will reclaim some of it, the >> application will >> start constantly thrashing. Since it code is placed on squashfs it spends >> whole CPU time >> decompressing the pages and seem memdelay counters are not detecting this >> situation. >> Here are some counters to indicate this: >> >> 19:02:44 CPU %user %nice %system %iowait %steal %idle >> 19:02:45 all 0.00 0.00 100.00 0.00 0.00 0.00 >> >> 19:02:44 pgpgin/s pgpgout/s fault/s majflt/s pgfree/s pgscank/s >> pgscand/s pgsteal/s %vmeff >> 19:02:45 15284.00 0.00 428.00 352.00 19990.00 0.00 0.00 >> 15802.00 0.00 >> >> And as nobody actively allocating memory anymore looks like memdelay >> counters are not >> actively incremented: >> >> [:~]$ cat /proc/memdelay >> 268035776 >> 6.13 5.43 3.58 >> 1.90 1.89 1.26 >> >> Just in case, I have attached the v4.9.26 rebased patched. >> > Looks like this 4.9 version does not contain the accounting in lock_page. In v4.9 there is no wait_on_page_bit_common(), thus accounting moved to wait_on_page_bit(_killable|_killable_timeout). Related functionality around lock_page_or_retry() seem to be mostly the same in v4.9. -- 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