Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751075AbbEAR7c (ORCPT ); Fri, 1 May 2015 13:59:32 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:38575 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750839AbbEAR73 (ORCPT ); Fri, 1 May 2015 13:59:29 -0400 Date: Fri, 1 May 2015 19:59:23 +0200 From: Ingo Molnar To: Rik van Riel Cc: Andy Lutomirski , "linux-kernel@vger.kernel.org" , X86 ML , williams@redhat.com, Andrew Lutomirski , fweisbec@redhat.com, Peter Zijlstra , Heiko Carstens , Thomas Gleixner , Ingo Molnar , Paolo Bonzini Subject: Re: [PATCH 3/3] context_tracking,x86: remove extraneous irq disable & enable from context tracking on syscall entry Message-ID: <20150501175923.GA1944@gmail.com> References: <554399D1.6010405@redhat.com> <20150501155912.GA451@gmail.com> <20150501162109.GA1091@gmail.com> <20150501163709.GC1327@gmail.com> <5543AC7E.5060602@redhat.com> <20150501164526.GB1548@gmail.com> <5543AFDC.6010204@redhat.com> <20150501171224.GC1657@gmail.com> <5543B64D.4040908@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5543B64D.4040908@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 925 Lines: 27 * Rik van Riel wrote: > > I.e. much of what we do today, except that we could skip variable > > work such as the scheduler tick or (unforced) RCU processing like > > the RCU softirq work. > > Any ideas how we could avoid that sampling timer interrupt latency > stacking up when dealing with both guest and host? Well, it would be host_latency+guest_latency worst-case, right? That should still be bounded, as long as both guest and host is running nohz-full mode. Also, technically when the host gets such an IRQ, the guest is interrupted as well. So the host could do the guest's work and pass through the result via paravirt or so. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/