From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 2E10F6B0292 for ; Mon, 26 Jun 2017 01:28:12 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id f49so27257622wrf.5 for ; Sun, 25 Jun 2017 22:28:12 -0700 (PDT) Received: from mail-wr0-x232.google.com (mail-wr0-x232.google.com. [2a00:1450:400c:c0c::232]) by mx.google.com with ESMTPS id o63si10682466wme.171.2017.06.25.22.28.10 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 25 Jun 2017 22:28:10 -0700 (PDT) Received: by mail-wr0-x232.google.com with SMTP id c11so136521400wrc.3 for ; Sun, 25 Jun 2017 22:28:10 -0700 (PDT) Subject: Re: [Bug 196157] New: 100+ times slower disk writes on 4.x+/i386/16+RAM, compared to 3.x References: <20170622123736.1d80f1318eac41cd661b7757@linux-foundation.org> <20170623071324.GD5308@dhcp22.suse.cz> <3541d6c3-6c41-8210-ee94-fef313ecd83d@gmail.com> <20170623113837.GM5308@dhcp22.suse.cz> From: Alkis Georgopoulos Message-ID: Date: Mon, 26 Jun 2017 08:28:07 +0300 MIME-Version: 1.0 In-Reply-To: <20170623113837.GM5308@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Andrew Morton , linux-mm@kvack.org, bugzilla-daemon@bugzilla.kernel.org, Mel Gorman , Johannes Weiner IGBPI?I1I? 23/06/2017 02:38 I 1/4 I 1/4 , I? Michal Hocko I-I3I?I+-I?Iu: > this means that the highmem is not dirtyable and so only 20% of the free > lowmem (+ page cache in that region) is considered and writers might > get throttled quite early (this might be a really low number when the > lowmem is congested already). Do you see the same problem when enabling > highmem_is_dirtyable = 1? > Excellent advice! :) Indeed, setting highmem_is_dirtyable=1 completely eliminates the issue! Is that something that should be =1 by default, i.e. should I notify the Ubuntu developers that the defaults they ship aren't appropriate, or is it something that only 16+ GB RAM memory owners should adjust in their local configuration? Thanks a lot! Results of 2 test runs, with highmem_is_dirtyable=0 and 1: 1) echo 0 > highmem_is_dirtyable: ----------------------------------------------------------------------------- 16.04.2 LTS (Xenial Xerus), 4.8.0-56-generic, i386, RAM=16292548 ----------------------------------------------------------------------------- Copying /lib to 1: 18.60 Copying 1 to 2: 6.09 Copying 2 to 3: 6.04 Copying 3 to 4: 7.04 Copying 4 to 5: 6.28 Copying 5 to 6: 5.03 Copying 6 to 7: 6.50 Copying 7 to 8: 4.82 Copying 8 to 9: 5.49 Copying 9 to 10: 5.88 Copying 10 to 11: 5.09 Copying 11 to 12: 5.70 Copying 12 to 13: 5.19 Copying 13 to 14: 4.55 Copying 14 to 15: 4.69 Copying 15 to 16: 4.76 Copying 16 to 17: 5.38 Copying 17 to 18: 4.59 Copying 18 to 19: 4.26 Copying 19 to 20: 4.47 Copying 20 to 21: 4.32 Copying 21 to 22: 4.33 Copying 22 to 23: 5.55 Copying 23 to 24: 4.73 Copying 24 to 25: 4.80 Copying 25 to 26: 5.06 Copying 26 to 27: 16.84 Copying 27 to 28: 5.28 Copying 28 to 29: 5.45 Copying 29 to 30: 12.35 Copying 30 to 31: 5.90 Copying 31 to 32: 4.90 Copying 32 to 33: 4.76 Copying 33 to 34: 4.37 Copying 34 to 35: 5.82 Copying 35 to 36: 4.55 Copying 36 to 37: 8.80 Copying 37 to 38: 5.07 Copying 38 to 39: 5.69 Copying 39 to 40: 4.88 Copying 40 to 41: 5.26 Copying 41 to 42: 4.69 Copying 42 to 43: 5.10 Copying 43 to 44: 4.79 Copying 44 to 45: 4.54 Copying 45 to 46: 7.46 Copying 46 to 47: 5.54 Copying 47 to 48: 4.86 Copying 48 to 49: 6.12 Copying 49 to 50: 5.37 Copying 50 to 51: 7.63 Copying 51 to 52: 6.37 Copying 52 to 53: 5.81 ... 2) echo 1 > highmem_is_dirtyable: ----------------------------------------------------------------------------- 16.04.2 LTS (Xenial Xerus), 4.8.0-56-generic, i386, RAM=16292548 ----------------------------------------------------------------------------- Copying /lib to 1: 21.47 Copying 1 to 2: 5.54 Copying 2 to 3: 6.63 Copying 3 to 4: 4.69 Copying 4 to 5: 5.38 Copying 5 to 6: 8.50 Copying 6 to 7: 9.34 Copying 7 to 8: 8.78 Copying 8 to 9: 9.48 Copying 9 to 10: 10.89 Copying 10 to 11: 10.52 Copying 11 to 12: 11.28 Copying 12 to 13: 14.70 Copying 13 to 14: 17.71 Copying 14 to 15: 52.43 Copying 15 to 16: 92.52 ... -- 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