Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753644AbcC3PH5 (ORCPT ); Wed, 30 Mar 2016 11:07:57 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:51138 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751895AbcC3PHz (ORCPT ); Wed, 30 Mar 2016 11:07:55 -0400 Date: Wed, 30 Mar 2016 17:07:47 +0200 From: Peter Zijlstra To: Daniel Wagner Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Thomas Gleixner , Sebastian Andrzej Siewior , Daniel Wagner Subject: Re: [RFC v1] sched/completion: convert completions to use simple wait queues Message-ID: <20160330150747.GY3408@twins.programming.kicks-ass.net> References: <1459349585-6527-1-git-send-email-wagi@monom.org> <1459349585-6527-2-git-send-email-wagi@monom.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1459349585-6527-2-git-send-email-wagi@monom.org> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 602 Lines: 13 On Wed, Mar 30, 2016 at 04:53:05PM +0200, Daniel Wagner wrote: > From: Daniel Wagner > > Completions have no long lasting callbacks and therefore do not need > the complex waitqueue variant. Use simple waitqueues which reduces > the contention on the waitqueue lock. Changelog really should have talk about the determinism thing. The last time you posted this the point was raised that we should wake the highest prio waiter in the defer case, you did not address this. Also, you make no mention of the reduction of UINT_MAX to USHORT_MAX and the implications of that.