netdev - Re: select(0, ..) is valid ?

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Message-Id: <200705181521.34339.ak@suse.de>
Date:	Fri, 18 May 2007 15:21:33 +0200
From:	Andi Kleen <ak@...e.de>
To:	Anton Blanchard <anton@...ba.org>
Cc:	Hugh Dickins <hugh@...itas.com>,
	Christoph Lameter <clameter@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Badari Pulavarty <pbadari@...ibm.com>, netdev@...r.kernel.org,
	lkml <linux-kernel@...r.kernel.org>, sfr@...b.auug.org.au
Subject: Re: select(0, ..) is valid ?

On Wednesday 16 May 2007 17:37, Anton Blanchard wrote:
> Hi Hugh,
>
> > It's interesting that compat_core_sys_select() shows this kmalloc(0)
> > failure but core_sys_select() does not.  That's because core_sys_select()
> > avoids kmalloc by using a buffer on the stack for small allocations (and
> > 0 sure is small).  Shouldn't compat_core_sys_select() do just the same?
> > Or is SLUB going to be so efficient that doing so is a waste of time?
>
> Nice catch, the original optimisation from Andi is:
>
> http://git.kernel.org/git-new/?p=linux/kernel/git/torvalds/linux-2.6.git;a=
>commit;h=70674f95c0a2ea694d5c39f4e514f538a09be36f
>
> And I think it makes sense for the compat code to do it too.

Yes agreed. I just forgot the copy'n'pasted code when doing the original
change.

-Andi
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