From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: Re: your mail Date: Wed, 16 Nov 2016 09:25:43 -0500 Message-ID: <20161116092543.663e1d2c@gandalf.local.home> References: <20161116104014.GQ3142@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Christoph Lameter , Daniel Vacek , Daniel Bristot de Oliveira , Tommaso Cucinotta , LKML , linux-rt-users , Ingo Molnar To: Peter Zijlstra Return-path: Received: from smtprelay0016.hostedemail.com ([216.40.44.16]:45996 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751277AbcKPOZr (ORCPT ); Wed, 16 Nov 2016 09:25:47 -0500 In-Reply-To: <20161116104014.GQ3142@twins.programming.kicks-ass.net> Sender: linux-rt-users-owner@vger.kernel.org List-ID: On Wed, 16 Nov 2016 11:40:14 +0100 Peter Zijlstra wrote: > On top of which, the implementation had issues; now I know you're the > blinder kind of person that disregards everything not in his immediate > interest, but if you'd looked at the patch you'd have seen he'd added > code the idle entry path, which will slow down every single to-idle > transition. Isn't to-idle a bit bloated anyway? Or has that been fixed. I know there was some issues with idle_balance() which can add latency to wakeups. idle_balance() is also in the to-idle path. Note, that this is a sched feature which would be a nop (jump_label) when disabled. And I'm sure it could also be optimized to be a static inline as well when it is enabled. I'm not saying we need to go this approach, but I'm just saying that the to-idle issue is a bit of a red herring. -- Steve