linux-kernel - Re: [PATCH 3/6] x86,64: Simplify save

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Date:	Wed, 06 Jul 2011 11:20:49 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Jan Beulich <JBeulich@...ell.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/6] x86,64: Simplify save_regs()

On 07/06/2011 10:34 AM, Andi Kleen wrote:
> Frederic Weisbecker <fweisbec@...il.com> writes:
>>
>> I really did not think about code duplication, considering
>> it's better to optimize the irq entry path.
>>
>> What do you guys think? We can still revert the whole patchset.
> 
> FWIW I think it should be a macro, like it was in the original code.
> 
> Optimizing entry*.S for code size doesn't make a lot of sense.
> 

Code size, no.

*Path* size and cache/prefetch friendliness is another matter.
The subroutine is bad on that account, too, so yes, this really seems
like a losing proposition.

I'm not too fond of the gajillion obtuse macros we have, but subroutines
doesn't make it really any better.

	-hpa
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