netdev - Re: [PATCH] lib/checksum.c: optimize do

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Date:	Thu, 07 Jul 2011 04:52:34 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	abbotti@....co.uk
Cc:	ian.abbott@....co.uk, netdev@...r.kernel.org, arnd@...db.de,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib/checksum.c: optimize do_csum a bit

From: David Miller <davem@...emloft.net>
Date: Thu, 07 Jul 2011 04:36:25 -0700 (PDT)

> From: Ian Abbott <abbotti@....co.uk>
> Date: Thu, 7 Jul 2011 12:32:45 +0100
> 
>> On 07/07/11 12:29, David Miller wrote:
>>> From: Ian Abbott <abbotti@....co.uk>
>>> Date: Thu, 7 Jul 2011 12:18:49 +0100
>>> 
>>>> Reduce the number of variables modified by the loop in do_csum() by 1,
>>>> which seems like a good idea.  On Nios II (a RISC CPU with 3-operand
>>>> instruction set) it reduces the loop from 7 to 6 instructions, including
>>>> the conditional branch.
>>>>
>>>> Signed-off-by: Ian Abbott <abbotti@....co.uk>
>>> 
>>> I think you'll overshoot past the end of the buffer when there are
>>> trailing bytes to handle.
>>> 
>>> The whole reason we need the count variable is to handle those
>>> kinds of cases.
>> 
>> I don't think it does.  That's what the & ~3 was for.
> 
> Aha, yes that indeed makes it work.

I've applied this to net-next-2.6, thanks.
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