From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760940AbaCUNOn (ORCPT ); Fri, 21 Mar 2014 09:14:43 -0400 Received: from mail-ee0-f50.google.com ([74.125.83.50]:63065 "EHLO mail-ee0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760874AbaCUNOl (ORCPT ); Fri, 21 Mar 2014 09:14:41 -0400 Message-ID: <1395407680.6030.81.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: artem_fetishev@epam.com, peterz@infradead.org, kosaki.motohiro@jp.fujitsu.com, linux-kernel@vger.kernel.org Date: Fri, 21 Mar 2014 14:14:40 +0100 In-Reply-To: References: <20140321200248.GB6264@owamsq.epam.com> ,<1395393822.6030.59.camel@marge.simpson.net> 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 Fri, 2014-03-21 at 12:18 +0000, jimmie.davis@l-3com.com wrote: > As the submitter of the bug, let me give you my perspective. > SCHED_FIFO means run my task until it blocks or a higher priority task > pre-empts it. Period. It blocked. > > mlock() doesn't block. check the man page. > I don't see that specified. (or how it could be, but what do I know, IANIPL) > Any other way and you are not able to use priority based scheduling. Sure you can, allocate and lock down resources before entering critical sections. If you think donning a SCHED_FIFO super-suit should make your task unstoppable, you're gonna be very disappointed. Fact is if your Juggernaut bumps ever so gently into a contended sleeping variety lock (and in the rt kernel that means nearly every lock), it will block. -Mike