From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 11 Jan 2007 10:08:55 +1100 From: David Chinner Subject: Re: [REGRESSION] 2.6.19/2.6.20-rc3 buffered write slowdown Message-ID: <20070110230855.GF44411608@melbourne.sgi.com> References: <20070110223731.GC44411608@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: David Chinner , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Wed, Jan 10, 2007 at 03:04:15PM -0800, Christoph Lameter wrote: > On Thu, 11 Jan 2007, David Chinner wrote: > > > The performance and smoothness is fully restored on 2.6.20-rc3 > > by setting dirty_ratio down to 10 (from the default 40), so > > something in the VM is not working as well as it used to.... > > dirty_background_ratio is left as is at 10? Yes. > So you gain performance by switching off background writes via pdflush? Well, pdflush appears to be doing very little on both 2.6.18 and 2.6.20-rc3. In both cases kswapd is consuming 10-20% of a CPU and all of the pdflush threads combined (I've seen up to 7 active at once) use maybe 1-2% of cpu time. This occurs regardless of the dirty_ratio setting. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group -- 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