From: Andi Kleen <andi@firstfloor.org>
To: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
andi@firstfloor.org, linux-kernel@vger.kernel.org,
x86@kernel.org
Subject: Re: [PATCH] x86: Improve 64 bit __phys_addr call performance
Date: Wed, 10 Oct 2012 15:58:01 +0200 [thread overview]
Message-ID: <20121010135801.GW16230@one.firstfloor.org> (raw)
In-Reply-To: <20121009185057.15478.86075.stgit@gitlad.jf.intel.com>
> The second change was to streamline the code by making use of the carry flag
> on an add operation instead of performing a compare on a 64 bit value. The
> advantage to this is that it allows us to reduce the overall size of the call.
> On my Xeon E5 system the entire __phys_addr inline call consumes 30 bytes and
> 5 instructions. I also applied similar logic to the debug version of the
> function. My testing shows that the debug version of the function with this
> patch applied is slightly faster than the non-debug version without the patch.
Looks good. Thanks.
Probably should still split the callers though (or have a pa_symbol_fast
that does not do the check)
-Andi
next prev parent reply other threads:[~2012-10-10 13:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-09 18:50 [PATCH] x86: Improve 64 bit __phys_addr call performance Alexander Duyck
2012-10-10 13:58 ` Andi Kleen [this message]
2012-10-10 23:56 ` Alexander Duyck
2012-10-24 10:25 ` Ingo Molnar
2012-10-24 16:31 ` Alexander Duyck
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