From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f49.google.com (mail-wg0-f49.google.com [74.125.82.49]) by kanga.kvack.org (Postfix) with ESMTP id 36BBE6B0032 for ; Wed, 24 Jun 2015 05:16:53 -0400 (EDT) Received: by wgck11 with SMTP id k11so30779717wgc.0 for ; Wed, 24 Jun 2015 02:16:52 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id iy7si1769135wic.58.2015.06.24.02.16.50 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 24 Jun 2015 02:16:51 -0700 (PDT) Date: Wed, 24 Jun 2015 11:16:50 +0200 From: Michal Hocko Subject: Re: Write throughput impaired by touching dirty_ratio Message-ID: <20150624091650.GC32756@dhcp22.suse.cz> References: <1506191513210.2879@stax.localdomain> <558A69F8.2080304@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <558A69F8.2080304@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Mark Hills Cc: Vlastimil Babka , linux-mm@kvack.org, Mel Gorman , Johannes Weiner , LKML On Wed 24-06-15 10:27:36, Vlastimil Babka wrote: > [add some CC's] > > On 06/19/2015 05:16 PM, Mark Hills wrote: [...] > > The system is an HP xw6600, running i686 kernel. This happens whether How many CPUs does the machine have? > > internal SATA HDD, SSD or external USB drive is used. I first saw this on > > kernel 4.0.4, and 4.0.5 is also affected. OK so this is 32b kernel which might be the most important part. What is the value of /proc/sys/vm/highmem_is_dirtyable? Also how does your low mem vs higmem look when you are setting the ratio (cat /proc/zoneinfo)? It seems Vlastimil is right and a bogus ratelimit_pages is calculated and your writers are throttled every few pages. -- Michal Hocko SUSE Labs -- 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