From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753927Ab1LFTPy (ORCPT ); Tue, 6 Dec 2011 14:15:54 -0500 Received: from casper.infradead.org ([85.118.1.10]:55829 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753721Ab1LFTMh convert rfc822-to-8bit (ORCPT ); Tue, 6 Dec 2011 14:12:37 -0500 Message-ID: <1323198720.32012.84.camel@twins> Subject: Re: [PATCH 0/3] Use jump_label for sched_feat() From: Peter Zijlstra To: Jason Baron Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Mike Galbraith , Paul Turner , Arnaldo Carvalho de Melo Date: Tue, 06 Dec 2011 20:12:00 +0100 In-Reply-To: <20111206181000.GE2449@redhat.com> References: <20111206171534.429636558@chello.nl> <20111206181000.GE2449@redhat.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Mailer: Evolution 3.2.1- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-12-06 at 13:10 -0500, Jason Baron wrote: > On Tue, Dec 06, 2011 at 06:15:34PM +0100, Peter Zijlstra wrote: > > These patches implement sched_feat() using jump_labels. The first is a section > > mismatch fix. The second patch provides a little infrastructure and the third > > patch applies it to make sched_feat() use static_branch(). > > > > It uses static_branch() coupled with unlikely/likely in order to control the > > branch block position. I haven't checked if it works, but it likely doesn't, > > although it should. > > > > > > It doesn't. I played around with unlikely/likely a bit, and it > didn't seem to make a difference. Right, we should look at getting that fixed though.. I think its a very useful hint to have. > That said, jump_labels could still be > an improvement here - it be good if we had some numbers, I guess. Yeah, acme had some number on an older version of this patch.