From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753361AbYG1Xf3 (ORCPT ); Mon, 28 Jul 2008 19:35:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751146AbYG1XfU (ORCPT ); Mon, 28 Jul 2008 19:35:20 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:60675 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751030AbYG1XfS (ORCPT ); Mon, 28 Jul 2008 19:35:18 -0400 Date: Tue, 29 Jul 2008 01:34:55 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Jens Axboe , Andi Kleen , Linux Kernel Mailing List , Thomas Gleixner , "H. Peter Anvin" Subject: Re: x86: Is there still value in having a special tlb flush IPI vector? Message-ID: <20080728233455.GA2919@elte.hu> References: <488E534F.2030204@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <488E534F.2030204@goop.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian 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 * Jeremy Fitzhardinge wrote: > Now that normal smp_function_call is no longer an enormous bottleneck, > is there still value in having a specialised IPI vector for tlb > flushes? It seems like quite a lot of duplicate code. > > The 64-bit tlb flush multiplexes the various cpus across 8 vectors to > increase scalability. If this is a big issue, then the smp function > call code can (and should) do the same thing. (Though looking at it > more closely, the way the code uses the 8 vectors is actually a less > general way of doing what smp_call_function is doing anyway.) yep, and we could eliminate the reschedule IPI as well. Ingo