linux-kernel - RE: [patch-mm 21/23] x86-64 block irq balancing for timer

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Message-ID: <653FFBB4508B9042B5D43DC9E18836F50101D663@scsmsx415.amr.corp.intel.com>
Date:	Mon, 11 Jun 2007 12:24:33 -0700
From:	"Pallipadi, Venkatesh" <venkatesh.pallipadi@...el.com>
To:	"Arjan van de Ven" <arjan@...radead.org>,
	"Thomas Gleixner" <tglx@...utronix.de>
Cc:	"LKML" <linux-kernel@...r.kernel.org>,
	"Andrew Morton" <akpm@...l.org>, "Ingo Molnar" <mingo@...e.hu>,
	"Andi Kleen" <ak@...e.de>, "Chris Wright" <chrisw@...s-sol.org>
Subject: RE: [patch-mm 21/23] x86-64 block irq balancing for timer



This just makes x86_64 behave like i386 which sets the flag today.

With tick-broadcast, even though we handle timer tick happening
anywhere, it will be nice if timer always goes to CPU 0 and we then
broadcast to any other CPUs. This is not a must have patch from my
perspective. But, we should make i386 and x86_64 same. So, we need to
change either one.

Thanks,
Venki

>-----Original Message-----
>From: Arjan van de Ven [mailto:arjan@...radead.org] 
>Sent: Sunday, June 10, 2007 9:29 AM
>To: Thomas Gleixner
>Cc: LKML; Andrew Morton; Ingo Molnar; Andi Kleen; Pallipadi, 
>Venkatesh; Chris Wright
>Subject: Re: [patch-mm 21/23] x86-64 block irq balancing for timer
>
>this isn't needed actually.. the userspace irq balancer won't balance
>irq 0 anyway, and if the sysadmin has a REAL good reason to move this
>himself... then why shouldn't we let him?
>
>
>
>On Sun, 2007-06-10 at 09:44 +0000, Thomas Gleixner wrote:
>> plain text document attachment
>> (x86-64-clockevents-irq-balancing.patch)
>> From: Venki Pallipadi <venkatesh.pallipadi@...el.com>
>> 
>> Disable irq balancing on IRQ0.
>> 
>> Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
>> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Andi Kleen <ak@...e.de>
>> 
>> ---
>>  arch/x86_64/kernel/time.c |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> Index: linux-2.6.22-rc4-mm/arch/x86_64/kernel/time.c
>> ===================================================================
>> --- linux-2.6.22-rc4-mm.orig/arch/x86_64/kernel/time.c	
>2007-06-10 10:44:39.000000000 +0200
>> +++ linux-2.6.22-rc4-mm/arch/x86_64/kernel/time.c	
>2007-06-10 10:44:40.000000000 +0200
>> @@ -255,7 +255,7 @@ static unsigned int __init tsc_calibrate
>>  
>>  static struct irqaction irq0 = {
>>  	.handler	= timer_interrupt,
>> -	.flags		= IRQF_DISABLED | IRQF_IRQPOLL,
>> +	.flags		= IRQF_DISABLED | IRQF_IRQPOLL | 
>IRQF_NOBALANCING,
>>  	.mask		= CPU_MASK_NONE,
>>  	.name		= "timer"
>>  };
>
>-- 
>if you want to mail me at work (you don't), use arjan (at) 
>linux.intel.com
>Test the interaction between Linux and your BIOS via 
>http://www.linuxfirmwarekit.org
>
-
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