From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754753Ab0FXKam (ORCPT ); Thu, 24 Jun 2010 06:30:42 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:50861 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754449Ab0FXKal convert rfc822-to-8bit (ORCPT ); Thu, 24 Jun 2010 06:30:41 -0400 Subject: Re: [RFC][PATCH] irq_work From: Peter Zijlstra To: Andi Kleen Cc: Huang Ying , Ingo Molnar , "H.PeterA" <"nvin hpa"@zytor.com>, linux-kernel@vger.kernel.org In-Reply-To: <20100624102725.GA578@basil.fritz.box> References: <1277348698-17311-1-git-send-email-ying.huang@intel.com> <1277361352.1875.838.camel@laptop> <1277361791.3947.11.camel@yhuang-dev.sh.intel.com> <1277362073.1875.839.camel@laptop> <1277362243.3947.20.camel@yhuang-dev.sh.intel.com> <1277362680.1875.845.camel@laptop> <1277363069.3947.30.camel@yhuang-dev.sh.intel.com> <1277363993.1875.847.camel@laptop> <1277364453.3947.64.camel@yhuang-dev.sh.intel.com> <1277364727.1875.857.camel@laptop> <20100624102725.GA578@basil.fritz.box> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Date: Thu, 24 Jun 2010 12:30:09 +0200 Message-ID: <1277375409.1875.943.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2010-06-24 at 12:27 +0200, Andi Kleen wrote: > > True, but I really don't like the softirq thing, and I really don't care > > about !APIC machines, I probably couldn't buy one if I wanted to and its > > not like we have good MCE support for them now, so who cares. > > In theory you can run a machine with good MCE support in non APIC single > CPU mode. It wouldn't make much sense, but you could do it. > > Anyways, I don't think we need a lot of effort to handle this case, > but it would be better to not explicitely break it either. > > That's why the timer fallback in the original code was fine, this > basically never happens and even if there is a 5s delay from tickless > that's fine. Right, in that case I would very much prefer the simpler thing I proposed over all this softirq stuff, we can have the tick process the callbacks for really broken hardware (perf_events doesn't care since without a lapic there's no pmi anyway).