Subject: Re: [PATCH] use per cpu data for single cpu ipi calls
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       Steven Rostedt <rostedt@goodmis.org>, linux-kernel@vger.kernel.org,
       rusty@rustcorp.com.au, npiggin@suse.de, torvalds@linux-foundation.org,
       tglx@linutronix.de, arjan@infradead.org
In-Reply-To: <20090129111330.GB30738@elte.hu>
References: <alpine.DEB.1.10.0901281029150.25359@gandalf.stny.rr.com>
	 <200901290955.38940.rusty@rustcorp.com.au>
	 <alpine.DEB.1.10.0901281916400.9203@gandalf.stny.rr.com>
	 <20090128173039.cbc29e81.akpm@linux-foundation.org>
	 <1233218954.7835.11.camel@twins>  <20090129111330.GB30738@elte.hu>
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Date: Thu, 29 Jan 2009 12:41:56 +0100
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On Thu, 2009-01-29 at 12:13 +0100, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@infradead.org> wrote:
> 
> > > Can generic_smp_call_function_single_interrupt() ever see 
> > > CSD_FLAG_ALLOC set now?  If not, that kfree can go away.
> > 
> > Like said above, removing that kmalloc will hurt people.
> 
> the whole promise of generic-IPI seems to dwindle and we'll get back to 
> roughly where we started out from.

I'd not go that far, the per-cpu csd is a nice fallback, but removing
that kmalloc is just silly.

And I see no reason why arch specific could do any better (aside from
sparc which has fancy ipis).

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