From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756100AbYGaU54 (ORCPT ); Thu, 31 Jul 2008 16:57:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752912AbYGaU5s (ORCPT ); Thu, 31 Jul 2008 16:57:48 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:48058 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752201AbYGaU5r (ORCPT ); Thu, 31 Jul 2008 16:57:47 -0400 Date: Thu, 31 Jul 2008 22:57:26 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Peter Zijlstra , Nick Piggin , 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: <20080731205726.GE25138@elte.hu> References: <488E534F.2030204@goop.org> <200807291430.08220.nickpiggin@yahoo.com.au> <1217325288.7563.2.camel@twins> <200807292000.30690.nickpiggin@yahoo.com.au> <1217328351.7563.12.camel@twins> <4891FB0A.907@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4891FB0A.907@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: > Peter Zijlstra wrote: > > How about using just arch_send_call_function_single_ipi() to implement > > smp_send_reschedule() ? > > > > The overhead of that is a smp_mb() and a list_empty() check in > > generic_smp_call_function_single_interrupt() if there is indeed no work > > to do. > > Is doing a no-op interrupt sufficient on all architectures? Is there > some change a function call IPI might not go through the normal > reschedule interrupt exit path? We'd still use the smp_send_reschdule(cpu) API, so it's an architecture detail. On x86 we'd use arch_send_call_function_single_ipi(). Ingo