From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756554Ab1JCPoA (ORCPT ); Mon, 3 Oct 2011 11:44:00 -0400 Received: from arkanian.console-pimps.org ([212.110.184.194]:54930 "EHLO arkanian.console-pimps.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754335Ab1JCPn4 (ORCPT ); Mon, 3 Oct 2011 11:43:56 -0400 Subject: Re: [RFC][PATCH 0/5] Signal scalability series From: Matt Fleming To: Linus Torvalds Cc: Andi Kleen , Oleg Nesterov , Tejun Heo , linux-kernel@vger.kernel.org, Tony Luck , Thomas Gleixner , Peter Zijlstra , David Mosberger-Tang In-Reply-To: References: <1317395577-14091-1-git-send-email-matt@console-pimps.org> <1317461738.3375.46.camel@mfleming-mobl1.ger.corp.intel.com> Content-Type: text/plain; charset="UTF-8" Date: Mon, 03 Oct 2011 16:43:33 +0100 Message-ID: <1317656613.3375.78.camel@mfleming-mobl1.ger.corp.intel.com> Mime-Version: 1.0 X-Mailer: Evolution 2.32.2 (2.32.2-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-10-03 at 08:28 -0700, Linus Torvalds wrote: > On Sat, Oct 1, 2011 at 2:35 AM, Matt Fleming wrote: > > > > You and me both. Unfortunately, the ia64 guys had a different opinion, > > http://www.spinics.net/lists/linux-ia64/msg08363.html > > Well, considering that it apparently slows down the single-threaded > case by 50% on an architecture that actually *matters*, I think the > whole discussion is somewhat academic, don't you? > > "Scalability" is pretty much never a valid excuse for "slows down the > common case". Where did you get the 50% slow down figure from? Oh, are you referring to Oleg's email about the slow down under kvm? Yeah, admittedly that's a pretty clear indicator that something is wrong with the approach in this patch series. I thought I'd replied to that email but I guess not. -- Matt Fleming, Intel Open Source Technology Center