Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755080Ab0FHS4P (ORCPT ); Tue, 8 Jun 2010 14:56:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:22652 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753477Ab0FHS4O (ORCPT ); Tue, 8 Jun 2010 14:56:14 -0400 Subject: Re: RFC: dirty_ratio back to 40% From: Larry Woodman To: Christoph Hellwig Cc: LKML , linux-mm In-Reply-To: <20100608184913.GA12154@infradead.org> References: <4BF51B0A.1050901@redhat.com> <20100608184913.GA12154@infradead.org> Content-Type: text/plain Date: Tue, 08 Jun 2010 15:01:24 -0400 Message-Id: <1276023684.8736.51.camel@dhcp-100-19-198.bos.redhat.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2386 Lines: 62 On Tue, 2010-06-08 at 14:49 -0400, Christoph Hellwig wrote: > Did this patch get merged somewhere? I dont think it ever did, about 1/2 of responses were for it and the other 1/2 against it. Larry > > On Thu, May 20, 2010 at 07:20:42AM -0400, Larry Woodman wrote: > > We've seen multiple performance regressions linked to the lower(20%) > > dirty_ratio. When performing enough IO to overwhelm the background > > flush daemons the percent of dirty pagecache memory quickly climbs > > to the new/lower dirty_ratio value of 20%. At that point all > > writing processes are forced to stop and write dirty pagecache pages > > back to disk. This causes performance regressions in several > > benchmarks as well as causing > > a noticeable overall sluggishness. We all know that the dirty_ratio is > > an integrity vs performance trade-off but the file system journaling > > will cover any devastating effects in the event of a system crash. > > > > Increasing the dirty_ratio to 40% will regain the performance loss seen > > in several benchmarks. Whats everyone think about this??? > > > > > > > > > > > > ------------------------------------------------------------------------ > > > > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > > index ef27e73..645a462 100644 > > --- a/mm/page-writeback.c > > +++ b/mm/page-writeback.c > > @@ -78,7 +78,7 @@ int vm_highmem_is_dirtyable; > > /* > > * The generator of dirty data starts writeback at this percentage > > */ > > -int vm_dirty_ratio = 20; > > +int vm_dirty_ratio = 40; > > > > /* > > * vm_dirty_bytes starts at 0 (disabled) so that it is a function of > > > > -- > > 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 > ---end quoted text--- > > -- > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/