Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750743AbVJGHuS (ORCPT ); Fri, 7 Oct 2005 03:50:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750904AbVJGHuR (ORCPT ); Fri, 7 Oct 2005 03:50:17 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:21938 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1750743AbVJGHuQ (ORCPT ); Fri, 7 Oct 2005 03:50:16 -0400 Subject: Re: [RFC] add sysfs to dynamically control blk request tag maintenance From: Arjan van de Ven To: Jens Axboe Cc: "Chen, Kenneth W" , linux-kernel@vger.kernel.org In-Reply-To: <20051007074138.GP2889@suse.de> References: <20051007074138.GP2889@suse.de> Content-Type: text/plain Date: Fri, 07 Oct 2005 09:50:07 +0200 Message-Id: <1128671408.2921.12.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit X-Spam-Score: 2.9 (++) X-Spam-Report: SpamAssassin version 3.0.4 on pentafluge.infradead.org summary: Content analysis details: (2.9 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- 0.1 RCVD_IN_SORBS_DUL RBL: SORBS: sent directly from dynamic IP address [80.57.133.107 listed in dnsbl.sorbs.net] 2.8 RCVD_IN_DSBL RBL: Received via a relay in list.dsbl.org [] X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 822 Lines: 18 On Fri, 2005-10-07 at 09:41 +0200, Jens Axboe wrote: > Ok that makes more sense! But it's a little worrying that > blk_queue_end_tag() would show up as hot in the profile, it is actually > quite lean. it probably just is the first one to touch the IO structures after the completion, and thus gets the penalty for the cachemiss. Something has to have that after io completion (the io started usually > 10 msec ago after all, and usually on another cpu at that) and my experience is that it's one of those jello elephants; you can only move it around but not really avoid it. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/