From: David Miller <davem@davemloft.net>
To: haoki@redhat.com
Cc: herbert@gondor.apana.org.au, netdev@vger.kernel.org,
satoshi.oshima.fk@hitachi.com, andi@firstfloor.org,
shemminger@linux-foundation.org, johnpol@2ka.mipt.ru,
yoshfuji@linux-ipv6.org, yumiko.sugita.yf@hitachi.com
Subject: Re: [PATCH 2/5] accounting unit and variable
Date: Tue, 13 Nov 2007 19:55:49 -0800 (PST) [thread overview]
Message-ID: <20071113.195549.181119456.davem@davemloft.net> (raw)
In-Reply-To: <473A6B11.7090208@redhat.com>
From: Hideo AOKI <haoki@redhat.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.
next prev parent reply other threads:[~2007-11-14 3:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-29 21:18 [PATCH 0/5] UDP memory accounting and limitation (take 6) Hideo AOKI
2007-10-29 21:22 ` [PATCH 1/5] fix send buffer check Hideo AOKI
2007-11-09 12:24 ` Herbert Xu
2007-11-14 3:25 ` Hideo AOKI
2007-10-29 21:23 ` [PATCH 2/5] accounting unit and variable Hideo AOKI
2007-11-09 12:34 ` Herbert Xu
2007-11-14 3:27 ` Hideo AOKI
2007-11-14 3:45 ` Herbert Xu
2007-11-14 3:55 ` David Miller [this message]
2007-11-14 15:32 ` Hideo AOKI
2007-11-14 23:30 ` Hideo AOKI
2007-11-15 1:09 ` Herbert Xu
2007-11-15 21:37 ` Hideo AOKI
2007-10-29 21:23 ` [PATCH 3/5] memory accounting Hideo AOKI
2007-11-09 13:07 ` Herbert Xu
2007-10-29 21:23 ` [PATCH 4/5] memory limitation by using udp_mem Hideo AOKI
2007-10-29 21:23 ` [PATCH 5/5] introduce udp_rmem and udp_wmem Hideo AOKI
2007-10-30 4:52 ` Bill Fink
2007-11-02 15:42 ` Hideo AOKI
-- strict thread matches above, loose matches on Subject: below --
2007-11-14 2:39 [PATCH 0/5] UDP memory accounting and limitation (take 7) Hideo AOKI
2007-11-14 2:48 ` [PATCH 2/5] accounting unit and variable Hideo AOKI
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