From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752741Ab1ECGbp (ORCPT ); Tue, 3 May 2011 02:31:45 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:45429 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751810Ab1ECGbo (ORCPT ); Tue, 3 May 2011 02:31:44 -0400 Date: Tue, 3 May 2011 08:31:30 +0200 From: Ingo Molnar To: Cyrill Gorcunov Cc: Suresh Siddha , LKML Subject: Re: [patch 1/2] x86, x2apic: minimize IPI register writes using cluster groups v4 Message-ID: <20110503063130.GC7751@elte.hu> References: <20110502113445.751391656@openvz.org> <20110502114024.222582172@openvz.org> <20110502132232.GA3873@elte.hu> <4DBEB96A.8000309@openvz.org> <4DBEBE72.3040702@gmail.com> <20110502150552.GA21974@elte.hu> <4DBECAB4.7020809@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4DBECAB4.7020809@gmail.com> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Cyrill Gorcunov wrote: > On 05/02/2011 07:05 PM, Ingo Molnar wrote: > ... > >> > >> Ingo, would it be fine to make apic->init() either _before_ this series or > >> on top of them (because if I introduce it inside this particular patch it > >> would contain some unrelated code snippets such as .init = NULL for all apics > >> declaration). > > > > Of course it should be a separate patch - even this patch looks a bit large - > > any way to split it up further? > > Well, for this particular path the only minimum is used, so i fear there is no > way to split it, probably I could drop some 'cleanup' bits from it and make it > a separate one. Gimme some time. Well, first try to do *all* preparatory and cleanup changes that have low regression risk. *Then* keep the most dangerous part to the end of it - so that it's easily reverted, should the need arise. Preferably the dangerous part should be much smaller than: 3 files changed, 136 insertions(+), 46 deletions(-) And no, it is not at all true that there is 'no way' to split the patch up any further: you could certainly add the data structures, init methods and such support code (which is low regression risk) in a separate patch than the changes that modify the existing x2apic_send_IPI_mask_allbutself() function and such. Also, the loop body in the new __x2apic_send_IPI_mask() function could certainly be split out into a helper inline, making the code flow clearer. Thanks, Ingo