Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755506AbZITSaQ (ORCPT ); Sun, 20 Sep 2009 14:30:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755451AbZITSaO (ORCPT ); Sun, 20 Sep 2009 14:30:14 -0400 Received: from mail-ew0-f206.google.com ([209.85.219.206]:43391 "EHLO mail-ew0-f206.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755448AbZITSaJ (ORCPT ); Sun, 20 Sep 2009 14:30:09 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=SgoiOV5jyEThfvTi3KjHd2W0xK2k+jAMHl/HS30X5MzRfy3KVGo89C7V88PGjgAonP 4/y7e9uOKex5dWObI6APWcvoso8VpUtC9MuLfii+aiMbLfY+bpJh6Kux8Ef13ONZIAx6 BFTx1gyPeNW/OMZsvAhcn+tnPqc9uBdZG32Gw= Date: Sun, 20 Sep 2009 22:30:11 +0400 From: Cyrill Gorcunov To: Ingo Molnar 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: <20090920183011.GC32176@lenovo> References: <1252403546-12544-1-git-send-email-sheng@linux.intel.com> <20090920180632.GB8498@elte.hu> <20090920181326.GB32176@lenovo> <20090920182124.GD8498@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090920182124.GD8498@elte.hu> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1882 Lines: 57 [Ingo Molnar - Sun, Sep 20, 2009 at 08:21:24PM +0200] | | * 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 | Well, I suppose we should wait for Sheng's comments. I wish I would answer you but I simply don't know Xen code :) -- Cyrill -- 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/