From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 17AAB6B007E for ; Tue, 8 Sep 2009 11:23:33 -0400 (EDT) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id C74D182C3BF for ; Tue, 8 Sep 2009 11:24:29 -0400 (EDT) Received: from smtp.ultrahosting.com ([74.213.174.253]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id YPpPT1B0PEAw for ; Tue, 8 Sep 2009 11:24:29 -0400 (EDT) Received: from V090114053VZO-1 (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 12EC882C3C5 for ; Tue, 8 Sep 2009 11:24:03 -0400 (EDT) Date: Tue, 8 Sep 2009 11:22:08 -0400 (EDT) From: Christoph Lameter Subject: Re: [rfc] lru_add_drain_all() vs isolation In-Reply-To: <1252419602.7746.73.camel@twins> Message-ID: References: <20090908190148.0CC9.A69D9226@jp.fujitsu.com> <1252405209.7746.38.camel@twins> <20090908193712.0CCF.A69D9226@jp.fujitsu.com> <1252411520.7746.68.camel@twins> <1252419602.7746.73.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Peter Zijlstra Cc: KOSAKI Motohiro , Mike Galbraith , Ingo Molnar , linux-mm , Oleg Nesterov , lkml List-ID: On Tue, 8 Sep 2009, Peter Zijlstra wrote: > There is _no_ functional difference between before and after, except > less wakeups on cpus that don't have any __lru_cache_add activity. > > If there's pages on the per cpu lru_add_pvecs list it will be present in > the mask and will be send a drain request. If its not, then it won't be > send. Ok I see. A global cpu mask like this will cause cacheline bouncing. After all this is a hot cpu path. Maybe do not set the bit if its already set (which may be very frequent)? Then add some benchmarks to show that it does not cause a regression on a 16p box (Nehalem) or so? -- 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