From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 04 Apr 2003 19:35:13 -0800 From: "Martin J. Bligh" Subject: Re: objrmap and vmtruncate Message-ID: <8090000.1049513712@[10.10.2.4]> In-Reply-To: <20030404192201.75794957.akpm@digeo.com> References: <20030404105417.3a8c22cc.akpm@digeo.com><20030404214547.GB16293@dualathlon.random><20030404150744.7e213331.akpm@digeo.com><20030405000352.GF16293@dualathlon.random><20030404163154.77f19d9e.akpm@digeo.com><12880000.1049508832@flay> <20030404192201.75794957.akpm@digeo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: andrea@suse.de, mingo@elte.hu, hugh@veritas.com, dmccr@us.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: >> > objrmap does not seem to help. Page clustering might, but is unlikely to >> > be enabled on the machines which actually care about the overhead. >> >> eh? Not sure what you mean by that. It helped massively ... >> diffprofile from kernbench showed: >> >> -4666 -74.9% page_add_rmap >> -10666 -92.0% page_remove_rmap >> >> I'd say that about an 85% reduction in cost is pretty damned fine ;-) >> And that was about a 20% overall reduction in the system time for the >> test too ... that was all for partial objrmap (file backed, not anon). > > In the test I use (my patch management scripts, which is basically bash > forking its brains out) objrmap reclaims only 30-50% of the rmap CPU > overhead. > > Maybe you had a very high sharing level. Not especially, I was running "make -j 32" for that one, which seems like a fairly small sharing load (though maybe a bit lighter than yours still). Going to high numbers of tasks will show even more impressive improvements. "make -j 256" actually looked reasonably similar. M. -- 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: aart@kvack.org