From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id A1EEC6B0024 for ; Mon, 9 May 2011 19:16:56 -0400 (EDT) Date: Mon, 9 May 2011 16:16:22 -0700 From: Andrew Morton Subject: Re: [PATCH 1/4] VM/RMAP: Add infrastructure for batching the rmap chain locking Message-Id: <20110509161622.57093622.akpm@linux-foundation.org> In-Reply-To: <20110509230255.GA6008@one.firstfloor.org> References: <1304623972-9159-1-git-send-email-andi@firstfloor.org> <1304623972-9159-2-git-send-email-andi@firstfloor.org> <20110509144324.8e79654a.akpm@linux-foundation.org> <4DC86947.30607@linux.intel.com> <20110509152841.ec957d23.akpm@linux-foundation.org> <20110509230255.GA6008@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: Andi Kleen , linux-mm@kvack.org, Andrea Arcangeli , Rik van Riel , tim.c.chen@linux.intel.com, torvalds@linux-foundation.org, lwoodman@redhat.com, mel@csn.ul.ie On Tue, 10 May 2011 01:02:55 +0200 Andi Kleen wrote: > On Mon, May 09, 2011 at 03:28:41PM -0700, Andrew Morton wrote: > > On Mon, 09 May 2011 15:23:03 -0700 > > Andi Kleen wrote: > > > > > > After fixing that and doing an allnoconfig x86_64 build, the patchset > > > > takes rmap.o's .text from 6167 bytes to 6551. This is likely to be a > > > > regression for uniprocessor machines. What can we do about this? > > > > > > > > > > Regression in what way? > > > > It makes the code larger and probably slower, for no gain? > > It should be actually faster because there are much less atomic ops. > Atomic ops are quite expensive -- especially on some older CPUs, even when > not contended. hm, which atomic ops are those? We shouldn't need buslocked operations on UP. > > > > > I guess I can move some of the functions out of > > > line. > > > > I don't know how much that will help. Perhaps a wholesale refactoring > > and making it all SMP-only will be justified. > > Yes I don't think there were a lot of callers. > > I can take out the lockbreak. I was a bit dubious on its utility > anyways. I guess that running something like latencytop with a suitably nasty workload would permit detection of any problems. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org