From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754792AbaEFPIX (ORCPT ); Tue, 6 May 2014 11:08:23 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40202 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751921AbaEFPIW (ORCPT ); Tue, 6 May 2014 11:08:22 -0400 Message-ID: <1399388899.5192.273.camel@marge.simpson.net> Subject: Re: Slow down stupid pounders From: Mike Galbraith To: Borislav Petkov Cc: lkml , x86-ml , Peter Zijlstra , Mel Gorman , Steven Rostedt Date: Tue, 06 May 2014 17:08:19 +0200 In-Reply-To: <20140506102924.GA25013@pd.tnic> References: <20140506102924.GA25013@pd.tnic> 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 Tue, 2014-05-06 at 12:29 +0200, Borislav Petkov wrote: > Hi, > > so I'm getting sick'n'tired of all those bug reports of people pounding > cpu hotplug with stupid scripts. > > * We know cpu hotplug is fragile/buggy/crap/needs proper rewrite. > > * Stupid hotplugging script doesn't resemble any real use case - go use > a real benchmark/stress test to trigger bugs. > > So if we can't make pounders stop jerking off, let's make it > uninterestingly slow. Stupid patch below, it might be completely idiotic > to do it this way but at least starts the discussion about this being a > really annoying issue which needs some sort of dealing with. > > I dunno, we can make it configurable (which will probably defeat its > purpose partially), we can do some more fancy ratelimiting, per cpu, > whatever... we'll see. > > Opinions, flames? Rather than ratelimit the interface perhaps send a ratelimited note telling the user straight up that he's begging for trouble. We can ignore it when regression testing, and point it out to Joe Pounder should he fail to notice.. or be somewhat dense. -Mike