From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753252AbaC0Ffj (ORCPT ); Thu, 27 Mar 2014 01:35:39 -0400 Received: from mail-ee0-f49.google.com ([74.125.83.49]:33695 "EHLO mail-ee0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751378AbaC0Ffi (ORCPT ); Thu, 27 Mar 2014 01:35:38 -0400 Message-ID: <1395898535.5512.72.camel@marge.simpson.net> Subject: RE: Bug 71331 - mlock yields processor to lower priority process From: Mike Galbraith To: jimmie.davis@l-3com.com Cc: luto@amacapital.net, oneukum@suse.de, artem_fetishev@epam.com, peterz@infradead.org, kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org Date: Thu, 27 Mar 2014 06:35:35 +0100 In-Reply-To: References: <20140321200248.GB6264@owamsq.epam.com> ,<1395393822.6030.59.camel@marge.simpson.net> ,<1395408925.9455.3.camel@linux-fkkt.site> ,<1395412904.6030.126.camel@marge.simpson.net> <5333734E.2020600@mit.edu> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2014-03-27 at 04:20 +0000, jimmie.davis@l-3com.com wrote: > The example code submitted into bugzilla (chase back on the thread a > bit, there is a reference) shows the problem. > > Two threads, TaskA (high priority) and TaskB (low priority). Assigned > to the same processor, explicitly for the guarantee that only one of > them can execute at a time. Your priority based serialization guarantee does not exist. Tasks can be and are put to sleep. When that happens, a lower priority runnable task will run. Whether you like that fact or not, it remains a fact. If you don't want your lower priority task to run, why do you wake it?. -Mike >