From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id A25449000BD for ; Mon, 26 Sep 2011 09:49:08 -0400 (EDT) Received: by gwaa12 with SMTP id a12so6325418gwa.14 for ; Mon, 26 Sep 2011 06:49:06 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <1316940890-24138-1-git-send-email-gilad@benyossef.com> <1316940890-24138-6-git-send-email-gilad@benyossef.com> <1317022420.9084.57.camel@twins> <1317030352.9084.76.camel@twins> Date: Mon, 26 Sep 2011 16:49:06 +0300 Message-ID: Subject: Re: [PATCH 5/5] slub: Only IPI CPUs that have per cpu obj to flush From: Gilad Ben-Yossef Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Frederic Weisbecker , Russell King , Chris Metcalf , linux-mm@kvack.org, Christoph Lameter , Pekka Enberg , Matt Mackall On Mon, Sep 26, 2011 at 3:05 PM, Gilad Ben-Yossef wrote: >> The problem with a per-cpu cpumask is that you need to disable >> preemption over the whole for_each_online_cpu() scan and that's not >> really sane on very large machines as that can easily take a very long >> time indeed. > > hmm... I might be thick, but why disable the preemption with the > per-cpu cpumask at all? ... > > Does that makes sense or have I've gone over board with this concept? :-) Scratch that. The cpumask must be per cache or the patch doesn't make sense at all. So sadly the only sane place to put it is in struct kmem_cache. I think we can still update the cpumask field without caring about preemption for the reasons stated above, but the per cache memory overhead is still there I'm afraid. Gilad -- Gilad Ben-Yossef Chief Coffee Drinker gilad@benyossef.com Israel Cell: +972-52-8260388 US Cell: +1-973-8260388 http://benyossef.com "I've seen things you people wouldn't believe. Goto statements used to implement co-routines. I watched C structures being stored in registers. All those moments will be lost in time... like tears in rain... Time to die. " -- 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