Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932223AbWCOK1S (ORCPT ); Wed, 15 Mar 2006 05:27:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932263AbWCOK1S (ORCPT ); Wed, 15 Mar 2006 05:27:18 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:2749 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S932223AbWCOK1S (ORCPT ); Wed, 15 Mar 2006 05:27:18 -0500 Subject: Re: [Patch 3/9] Block I/O accounting initialization From: Arjan van de Ven To: nagar@watson.ibm.com Cc: linux-kernel , Andi Kleen In-Reply-To: <1142297222.5858.13.camel@elinux04.optonline.net> References: <1142296834.5858.3.camel@elinux04.optonline.net> <1142297222.5858.13.camel@elinux04.optonline.net> Content-Type: text/plain Date: Wed, 15 Mar 2006 11:27:15 +0100 Message-Id: <1142418436.3021.13.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit 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: 723 Lines: 21 > > +static inline void delayacct_blkio_start(void) > +{ > + if (unlikely(delayacct_on)) > + __delayacct_blkio_start(); > +} I still think the unlikely() makes no sense here; at runtime it's either going to be always on or off (in the sense that switching it will be RARE). The cpus branch predictor will get that right; while if you force it unlikely you can even run the risk of getting a 100% miss on some architectures (not x86/x86-64) when you enable the accounting - 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/