From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758212Ab3JKNvR (ORCPT ); Fri, 11 Oct 2013 09:51:17 -0400 Received: from science.horizon.com ([71.41.210.146]:50573 "HELO science.horizon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753710Ab3JKNvQ (ORCPT ); Fri, 11 Oct 2013 09:51:16 -0400 Date: 11 Oct 2013 09:51:14 -0400 Message-ID: <20131011135114.24362.qmail@science.horizon.com> From: "George Spelvin" To: linux@horizon.com, rostedt@goodmis.org Subject: Re: [PATCH 0/6] Optimize the cpu hotplug locking -v2 Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, peterz@infradead.org, srivatsa.bhat@linux.vnet.ibm.com, torvalds@linux-foundation.org In-Reply-To: <20131011084507.1d691504@gandalf.local.home> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > The problem is that the scheduler doesn't see that the current task has > preemption disabled. It only looks at the priorities of the current > task, and if it can preempt it, it will. It sets the NEED_RESCHED to the > current task and waits for the preemption to schedule it out. Ah, got it. It's a priority inversion problem, and while there is a standard solution (priority inheritance), if I were to suggest such a heavyweight solution, Linus would start yelling again and Sarah would get unhappy, and we all know how that ends up. Thank you. I will now cease displaying my ignorance in public.