From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 1/4 tip/sched/core] sched: rename preempt_notifier to sched_notifier and always enable it Date: Fri, 27 Nov 2009 06:46:21 +0100 Message-ID: <20091127054621.GA25672@elte.hu> References: <20091126095154.GE32275@elte.hu> <4B0E5458.30303@kernel.org> <20091126102936.GA1196@elte.hu> <1259231565.4273.31.camel@twins> <1259234619.4273.32.camel@twins> <20091126115605.GA15189@elte.hu> <1259239259.4273.82.camel@twins> <4B0F356B.3040206@kernel.org> <20091127045209.GA13914@elte.hu> <4B0F65DD.1090707@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:43902 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149AbZK0Fqo (ORCPT ); Fri, 27 Nov 2009 00:46:44 -0500 Content-Disposition: inline In-Reply-To: <4B0F65DD.1090707@kernel.org> Sender: linux-next-owner@vger.kernel.org List-ID: To: Tejun Heo Cc: Peter Zijlstra , Steven Rostedt , Fr??d??ric Weisbecker , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Mike Galbraith , Thomas Gleixner , "H. Peter Anvin" * Tejun Heo wrote: > Hello, > > 11/27/2009 01:52 PM, Ingo Molnar wrote: > > Btw., longer term it will be faster than a mask check and a > > default-untaken conditional: there's ongoign work to offer runtime > > instruction patching features for tracing callbacks. There's the > > jump patching optimization and also the immediate values patching > > optimization. > > Scheduler callbacks won't benefit much from it. There will always be > workqueues and thus conditional branch will always be necessary. Other code will benefit from it though, such as the page fault callbacks i already mentioned. My position on this is rather clear: i want no new callbacks and no changes to callbacks in the scheduler until this situation is cleaned up. Five callback sites are _way_ too much - so if you want to add callbacks or change them, please clean it up and improve it first. Ingo