netdev - Re: [PATCH 2/5] accounting unit and variable

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Message-ID: <473B150A.8050208@redhat.com>
Date:	Wed, 14 Nov 2007 10:32:26 -0500
From:	Hideo AOKI <haoki@...hat.com>
To:	David Miller <davem@...emloft.net>, herbert@...dor.apana.org.au
CC:	netdev@...r.kernel.org, satoshi.oshima.fk@...achi.com,
	andi@...stfloor.org, shemminger@...ux-foundation.org,
	johnpol@....mipt.ru, yoshfuji@...ux-ipv6.org,
	yumiko.sugita.yf@...achi.com
Subject: Re: [PATCH 2/5] accounting unit and variable

David Miller wrote:
> From: Hideo AOKI <haoki@...hat.com>
> Date: Tue, 13 Nov 2007 22:27:13 -0500
> 
>> Herbert Xu wrote:
>>> On Mon, Oct 29, 2007 at 05:23:10PM -0400, Hideo AOKI wrote:
>>>>  
>>>> +#define SK_DATAGRAM_MEM_QUANTUM ((int)PAGE_SIZE)
>>>> +
>>>> +static inline int sk_datagram_pages(int amt)
>>>> +{
>>>> +	return DIV_ROUND_UP(amt, SK_DATAGRAM_MEM_QUANTUM);
>>>> +}
>>> Does this really have to be int? Unsigned would let the compiler
>>> optimise this to a simple shift.
>> Thank you for the comment.
>>
>> This inline function is used to calculate the first argument of atomic_add()
>> and atomic_sub(). Since the argument is int, I believe that using int is
>> better than using unsigned int.
> 
> If you know the values will always be positive, as you will know here,
> it is OK to us unsigned int here and avoids the unacceptable expensive
> divide instruction.
> 
> Please fix this.

Hello,

Thanks for your comments. I finally understood.

I'll fix it and resubmit the patch as soon as possible.

Regards,
Hideo

--
Hitachi Computer Products (America) Inc.

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