Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753769AbaBMJiH (ORCPT ); Thu, 13 Feb 2014 04:38:07 -0500 Received: from mail-ea0-f169.google.com ([209.85.215.169]:45548 "EHLO mail-ea0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753190AbaBMJiD (ORCPT ); Thu, 13 Feb 2014 04:38:03 -0500 Date: Thu, 13 Feb 2014 10:38:00 +0100 From: Ingo Molnar To: Andy Lutomirski Cc: Peter Zijlstra , Thomas Gleixner , Mike Galbraith , X86 ML , linux-kernel@vger.kernel.org Subject: Re: [RFC] sched: Add a new lockless wake-from-idle implementation Message-ID: <20140213093800.GA6078@gmail.com> References: <20140212201709.GB6835@laptop.programming.kicks-ass.net> <218b548b69479baa005af8a7b04a3abbea8ed6fa.1392252790.git.luto@amacapital.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <218b548b69479baa005af8a7b04a3abbea8ed6fa.1392252790.git.luto@amacapital.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andy Lutomirski wrote: > This is a strawman proposal to simplify the idle implementation, eliminate > a race > > Benefits over current code: > - ttwu_queue_remote doesn't use an IPI unless needed Cool. > - The diffstat should speak for itself :) Neat! > - Less racy. Spurious IPIs are possible, but only in narrow windows or > when two wakeups occur in rapid succession. > - Seems to work (?) > > Issues: > - Am I doing the percpu stuff right? > - Needs work on non-x86 architectures Absolutely, and with the least amount of disruption possible, as people are not very good at testing 'all' of them. > - The !CONFIG_SMP case needs to be checked Which also happens to be the default for half of all non-x86 arches. > - Is "idlepoll" a good name for the new code? It doesn't have *that* > much to do with the idle state. Maybe cpukick? 'cpukick', hands down. > If this turns out okay, TIF_NEED_RESCHED could possibly be deleted as well. Cool ... Thanks, Ingo -- 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/