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Date: Tue, 22 Apr 2008 21:12:13 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <jens.axboe@oracle.com>, linux-arch@vger.kernel.org,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       npiggin@suse.de, peterz@infradead.org, sam@ravnborg.org
Subject: Re: [PATCH 2/11] x86: convert to generic helpers for IPI function
	calls
Message-ID: <20080422191213.GA6370@elte.hu>
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> 
> [ Ingo added to cc, since this is x86-specific ]
> 
> On Tue, 22 Apr 2008, Jens Axboe wrote:
> > +++ b/arch/x86/kernel/apic_32.c
> > @@ -1357,6 +1357,10 @@ void __init smp_intr_init(void)
> >  
> >  	/* IPI for generic function call */
> >  	set_intr_gate(CALL_FUNCTION_VECTOR, call_function_interrupt);
> > +
> > +	/* IPI for single call function */
> > +	set_intr_gate(CALL_FUNCTION_SINGLE_VECTOR,
> > +				call_function_single_interrupt);
> 
> Ok, one more comment..
> 
> Why bother with separate vectors for this?

this was my first question a month ago when Jens/Nick first submitted it
:)

> Or is it just a performance optimization? [...]

yes and i gave in - Nick and Jens wants to do some crazy stuff and they 
had the numbers. Here's the previous discussion:

  http://lkml.org/lkml/2008/2/27/125

	Ingo