linux-kernel - Re: [PATCH] x86: Add optimized popcnt variants

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Date:	Fri, 19 Feb 2010 08:53:32 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...64.org>
CC:	Michal Marek <mmarek@...e.cz>,
	linux-kbuild <linux-kbuild@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Jamie Lokier <jamie@...reable.org>,
	Roland Dreier <rdreier@...co.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, Brian Gerst <brgerst@...il.com>
Subject: Re: [PATCH] x86: Add optimized popcnt variants

On 02/19/2010 08:45 AM, Borislav Petkov wrote:
>>
>> You're still not inlining these.  They should be: there is absolutely no
>> reason for code size to not inline them anymore.
> 
> Isn't better to have only those 4 locations for apply_alternatives to
> patch wrt to popcnt instead of sprinkling alternatives sections around
> the kernel in every callsite of hweight and its users? Or is the aim to
> optimize even that "call __arch_hweightXX" away?
> 

That's the idea, yes.  We use inline alternatives in quite a few other
places.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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