From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id CCA949000BD for ; Mon, 26 Sep 2011 06:03:42 -0400 (EDT) Received: by bkbzs2 with SMTP id zs2so7278832bkb.14 for ; Mon, 26 Sep 2011 03:03:40 -0700 (PDT) Date: Mon, 26 Sep 2011 13:03:19 +0300 (EEST) From: Pekka Enberg Subject: Re: [PATCH 5/5] slub: Only IPI CPUs that have per cpu obj to flush In-Reply-To: Message-ID: References: <1316940890-24138-1-git-send-email-gilad@benyossef.com> <1316940890-24138-6-git-send-email-gilad@benyossef.com> <1317022565.9084.60.camel@twins> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: owner-linux-mm@kvack.org List-ID: To: Gilad Ben-Yossef Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, Frederic Weisbecker , Russell King , Chris Metcalf , linux-mm@kvack.org, Christoph Lameter , Matt Mackall On Mon, 26 Sep 2011, Gilad Ben-Yossef wrote: > Peter basically already answered better then I could :-) > > All I have to add is an example - > > flush_all() is called for each kmem_cahce_destroy(). So every cache > being destroyed dynamically ends up sending an IPI to each CPU in the > system, regardless if the cache has ever been used there. > > For example, if you close the Infinband ipath driver char device file, > the close file ops calls kmem_cache_destroy().So, if I understand > correctly, running some infiniband config tool on one a single CPU > dedicated to system tasks might interrupt the rest of the 127 CPUs I > dedicated to some CPU intensive task. This is the scenario I'm > tryingto avoid. > > I suspect there is a good chance that every line in the output of "git > grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario > (there are 42 of them). > > I hope this sheds some light on the motive of the work. Sure. If you write down such information in the changelog for future patches, I don't need to waste your time asking for an explanation. ;-) Pekka -- 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