From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752212AbaKUUXP (ORCPT ); Fri, 21 Nov 2014 15:23:15 -0500 Received: from mail-oi0-f50.google.com ([209.85.218.50]:45483 "EHLO mail-oi0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750939AbaKUUXO (ORCPT ); Fri, 21 Nov 2014 15:23:14 -0500 MIME-Version: 1.0 In-Reply-To: References: <20141120221122.GA25393@htj.dyndns.org> <20141120230514.GB25393@htj.dyndns.org> <20141120233920.GC25393@htj.dyndns.org> <20141121162742.GB15461@htj.dyndns.org> <20141121170805.GD30603@home.goodmis.org> <20141121142301.564f7eb7@gandalf.local.home> Date: Fri, 21 Nov 2014 15:23:13 -0500 X-Google-Sender-Auth: Pozhhf03YgossGDDXFWgBoT4MVE Message-ID: Subject: Re: frequent lockups in 3.18rc4 From: Josh Boyer To: Andy Lutomirski Cc: Linus Torvalds , Steven Rostedt , Tejun Heo , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Peter Zijlstra , Frederic Weisbecker , Don Zickus , Dave Jones , "the arch/x86 maintainers" Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 21, 2014 at 3:16 PM, Andy Lutomirski wrote: > On Fri, Nov 21, 2014 at 12:14 PM, Josh Boyer wrote: >> On Fri, Nov 21, 2014 at 2:52 PM, Andy Lutomirski wrote: >>> On Fri, Nov 21, 2014 at 11:46 AM, Linus Torvalds >>> wrote: >>>> On Fri, Nov 21, 2014 at 11:34 AM, Linus Torvalds >>>> wrote: >>>>> >>>>> So I kind of agree, but it wouldn't be my primary worry. My primary >>>>> worry is actually paravirt doing something insane. >>>> >>>> Btw, on that tangent, does anybody actually care about paravirt any more? >>>> >>> >>> Amazon, for better or for worse. >>> >>>> I'd love to start moving away from it. It makes a lot of the low-level >>>> code completely impossible to follow due to the random indirection >>>> through "native" vs "paravirt op table". Not just the page table >>>> handling, it's all over. >>>> >>>> Anybody who seriously does virtualization uses hw virtualization that >>>> is much better than it used to be. And the non-serious users aren't >>>> that performance-sensitive by definition. >>>> >>>> I note that the Fedora kernel config seems to include paravirt by >>>> default, so you get a lot of the crazy overheads.. >>> >>> I think that there is a move toward deprecating Xen PV in favor of >>> PVH, but we're not there yet. >> >> A move where? The Xen stuff in Fedora is ... not paid attention to >> very much. If there's something we should be looking at turning off >> (or on), we're happy to take suggestions. > > A move in the Xen project. As I understand it, Xen wants to deprecate > PV in favor of PVH, but PVH is still experimental. OK. > I think that dropping PARAVIRT in Fedora might be a bad idea for > several more releases, since that's likely to break the EC2 images. Yes, that's essentially the only reason we haven't looked at disabling Xen completely for a while now, so . josh