Re: [PATCH] add likely around access_ok for uaccess

From: Jeff Garzik
Date: Tue Sep 16 2003 - 15:56:40 EST


On Tue, Sep 16, 2003 at 09:49:29PM +0200, Pavel Machek wrote:
> Hi!
>
> > while trying to figure out why sysv msg is around 30% slower than pipes
> > for data transfers I noticed that gcc's autodetection (3.2.2) guesses
> > the "if(access_ok())" tests in uaccess.h wrong and puts the error memset
> > into the direct path and the copy out of line.
> >
> > The attached patch adds likely to the tests - any objections? What about
> > the archs except i386?
>
> How much speedup did you gain?

How much can it hurt?

Jeff



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