Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755309AbZITSVo (ORCPT ); Sun, 20 Sep 2009 14:21:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754910AbZITSVk (ORCPT ); Sun, 20 Sep 2009 14:21:40 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:33240 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754742AbZITSVj (ORCPT ); Sun, 20 Sep 2009 14:21:39 -0400 Date: Sun, 20 Sep 2009 20:21:24 +0200 From: Ingo Molnar To: Cyrill Gorcunov Cc: Sheng Yang , Yinghai Lu , Suresh Siddha , linux-kernel@vger.kernel.org, Dimitri Sivanich , Thomas Gleixner , "H. Peter Anvin" Subject: Re: [PATCH] x86: Don't ack_APIC_irq() if lapic is disabled in GENERIC_INTERRUPT_VECTOR handler Message-ID: <20090920182124.GD8498@elte.hu> References: <1252403546-12544-1-git-send-email-sheng@linux.intel.com> <20090920180632.GB8498@elte.hu> <20090920181326.GB32176@lenovo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090920181326.GB32176@lenovo> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 49 * Cyrill Gorcunov wrote: > [Ingo Molnar - Sun, Sep 20, 2009 at 08:06:32PM +0200] > | > | * Sheng Yang wrote: > | > | > Otherwise would cause trouble... > | > > | > Cc: Dimitri Sivanich > | > Signed-off-by: Sheng Yang > | > --- > | > arch/x86/kernel/irq.c | 3 ++- > | > 1 files changed, 2 insertions(+), 1 deletions(-) > | > > | > diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c > | > index b0cdde6..78b23d0 100644 > | > --- a/arch/x86/kernel/irq.c > | > +++ b/arch/x86/kernel/irq.c > | > @@ -257,7 +257,8 @@ void smp_generic_interrupt(struct pt_regs *regs) > | > { > | > struct pt_regs *old_regs = set_irq_regs(regs); > | > > | > - ack_APIC_irq(); > | > + if (!disable_apic) > | > + ack_APIC_irq(); > | > | Wont in that case the apic->ack method be a NOP? > | > | Ingo > | > > iirc it was Xen related patch. So it's not that simple. > > I've pointed out Sheng about disable_apic. I'm not Xen > specialist but Xen team seem to use specific apic setup > so our "dummy" operations are not involved (case they > set disable_apic=1 without "turn off" apic ops in real). > Something like that. They should then set a NOP function in that case. We really dont want to slow down hotpath functions like smp_generic_interrupt() with flaggery. 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/