From: Dave Jones <davej@redhat.com>
To: roel <12o3l@tiscali.nl>
Cc: travis@sgi.com, Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@suse.de>, Christoph Lameter <clameter@sgi.com>,
Jack Steiner <steiner@sgi.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] x86: Convert cpuinfo_x86 array to a per_cpu array v3
Date: Mon, 24 Sep 2007 20:31:27 -0400 [thread overview]
Message-ID: <20070925003127.GQ11455@redhat.com> (raw)
In-Reply-To: <46F85431.1020306@tiscali.nl>
On Tue, Sep 25, 2007 at 02:20:01AM +0200, roel wrote:
> > > > if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
> > > > ((c->x86_model != 12) && (c->x86_model != 13)))
> > >
> > > while we're at it, we could change this to
> > >
> > > if (!(c->x86_vendor == X86_VENDOR_AMD && c->x86 == 5 &&
> > > (c->x86_model == 12 || c->x86_model == 13)))
> >
> > For what purpose? There's nothing wrong with the code as it stands,
> > and inverting the tests means we'd have to move a bunch of
> > code inside the if arm instead of just returning -ENODEV.
>
> It's not inverting the test, so you don't need to move code. It evaluates
> the same, only the combined negation is moved to the front. I suggested it
> to increase clarity, it results in the same assembly language.
I don't see it as being particularly more readable after this change.
In fact, the reverse, as my previous comment implied, I missed the
initial !
Given this code works fine, and there's no discernable gain from
changing it, I'm not particularly enthusiastic about this modification.
Dave
--
http://www.codemonkey.org.uk
WARNING: multiple messages have this Message-ID (diff)
From: Dave Jones <davej@redhat.com>
To: roel <12o3l@tiscali.nl>
Cc: travis@sgi.com, Andrew Morton <akpm@linux-foundation.org>,
Andi Kleen <ak@suse.de>, Christoph Lameter <clameter@sgi.com>,
Jack Steiner <steiner@sgi.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] x86: Convert cpuinfo_x86 array to a per_cpu array v3
Date: Mon, 24 Sep 2007 20:31:27 -0400 [thread overview]
Message-ID: <20070925003127.GQ11455@redhat.com> (raw)
In-Reply-To: <46F85431.1020306@tiscali.nl>
On Tue, Sep 25, 2007 at 02:20:01AM +0200, roel wrote:
> > > > if ((c->x86_vendor != X86_VENDOR_AMD) || (c->x86 != 5) ||
> > > > ((c->x86_model != 12) && (c->x86_model != 13)))
> > >
> > > while we're at it, we could change this to
> > >
> > > if (!(c->x86_vendor == X86_VENDOR_AMD && c->x86 == 5 &&
> > > (c->x86_model == 12 || c->x86_model == 13)))
> >
> > For what purpose? There's nothing wrong with the code as it stands,
> > and inverting the tests means we'd have to move a bunch of
> > code inside the if arm instead of just returning -ENODEV.
>
> It's not inverting the test, so you don't need to move code. It evaluates
> the same, only the combined negation is moved to the front. I suggested it
> to increase clarity, it results in the same assembly language.
I don't see it as being particularly more readable after this change.
In fact, the reverse, as my previous comment implied, I missed the
initial !
Given this code works fine, and there's no discernable gain from
changing it, I'm not particularly enthusiastic about this modification.
Dave
--
http://www.codemonkey.org.uk
--
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next prev parent reply other threads:[~2007-09-25 0:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-24 21:08 [PATCH 0/1] x86: Convert cpuinfo_x86 array to a per_cpu array v3 travis
2007-09-24 21:08 ` travis
2007-09-24 21:08 ` [PATCH 1/1] " travis
2007-09-24 21:08 ` travis
2007-09-24 22:01 ` roel
2007-09-24 22:01 ` roel
2007-09-24 23:24 ` Dave Jones
2007-09-24 23:24 ` Dave Jones
2007-09-25 0:20 ` roel
2007-09-25 0:20 ` roel
2007-09-25 0:31 ` Dave Jones [this message]
2007-09-25 0:31 ` Dave Jones
2007-10-16 8:18 ` [PATCH 0/1] " Andrew Morton
2007-10-16 8:18 ` Andrew Morton
2007-08-04 1:15 ` Mike Travis
2007-08-04 1:15 ` Mike Travis
2007-10-16 15:02 ` Christoph Lameter
2007-10-16 15:02 ` Christoph Lameter
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