From: Arjan van de Ven <arjan@infradead.org>
To: linux-os@analogic.com
Cc: Jesper Juhl <juhl-lkml@dif.dk>,
Neil Brown <neilb@cse.unsw.edu.au>,
nfs@lists.sourceforge.net,
Trond Myklebust <trond.myklebust@fys.uio.no>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] remove redundant NULL pointer checks prior to calling kfree() in fs/nfsd/
Date: Sat, 26 Mar 2005 09:34:00 +0100 [thread overview]
Message-ID: <1111826041.6293.31.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <Pine.LNX.4.61.0503251731240.6372@chaos.analogic.com>
On Fri, 2005-03-25 at 17:34 -0500, linux-os wrote:
> On Fri, 25 Mar 2005, Jesper Juhl wrote:
>
> > (please keep me on CC)
> >
> >
> > checking for NULL before calling kfree() is redundant and needlessly
> > enlarges the kernel image, let's get rid of those checks.
> >
>
> Hardly. ORing a value with itself and jumping on condition is
> real cheap compared with pushing a value into the stack
which century are you from?
"jumping on condition" can easily be 100+ cycles, depending on how
effective the branch predictor is. Pushing a value onto the stack otoh
is half a cycle.
Your argument was right probably in 1994, when cpus didn't do
speculation and out of order execution...
next prev parent reply other threads:[~2005-03-26 8:36 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-25 22:22 Jesper Juhl
2005-03-25 22:34 ` linux-os
2005-03-25 23:12 ` Jesper Juhl
2005-03-26 8:34 ` Arjan van de Ven [this message]
2005-03-27 12:45 ` Denis Vlasenko
2005-03-27 14:30 ` Arjan van de Ven
2005-03-27 14:00 ` Pekka Enberg
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