From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756383AbbJHLUG (ORCPT ); Thu, 8 Oct 2015 07:20:06 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:59355 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756363AbbJHLUE (ORCPT ); Thu, 8 Oct 2015 07:20:04 -0400 Date: Thu, 8 Oct 2015 13:19:59 +0200 From: Peter Zijlstra To: paul.szabo@sydney.edu.au Cc: umgwanakikbuti@gmail.com, linux-kernel@vger.kernel.org Subject: Re: CFS scheduler unfairly prefers pinned tasks Message-ID: <20151008111959.GM3816@twins.programming.kicks-ass.net> References: <1444292390.3389.100.camel@gmail.com> <201510081054.t98AsL1U003456@como.maths.usyd.edu.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201510081054.t98AsL1U003456@como.maths.usyd.edu.au> 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 On Thu, Oct 08, 2015 at 09:54:21PM +1100, paul.szabo@sydney.edu.au wrote: > Good to see that you agree on the fairness issue... it MUST be fixed! > CFS might be wrong or wasteful, but never unfair. I've not yet had time to look at the case at hand, but there are wat is called 'infeasible weight' scenarios for which it is impossible to be fair. Also, CFS must remain a practical scheduler, which places bounds on the amount of weird cases we can deal with.