From: "H. Peter Anvin" <hpa@zytor.com>
To: Borislav Petkov <bp@amd64.org>
Cc: Michal Marek <mmarek@suse.cz>,
linux-kbuild <linux-kbuild@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Wu Fengguang <fengguang.wu@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Jamie Lokier <jamie@shareable.org>,
Roland Dreier <rdreier@cisco.com>,
Al Viro <viro@ZenIV.linux.org.uk>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Ingo Molnar <mingo@elte.hu>, Brian Gerst <brgerst@gmail.com>
Subject: Re: [PATCH] x86: Add optimized popcnt variants
Date: Thu, 25 Feb 2010 21:27:25 -0800 [thread overview]
Message-ID: <4B875BBD.4060104@zytor.com> (raw)
In-Reply-To: <20100223190614.GB2401@aftab>
On 02/23/2010 11:06 AM, Borislav Petkov wrote:
>
> Ok, here you go.
>
> --
> From: Borislav Petkov <borislav.petkov@amd.com>
> Date: Thu, 11 Feb 2010 00:48:31 +0100
> Subject: [PATCH] x86: Add optimized popcnt variants
>
> Add support for the hardware version of the Hamming weight function,
> popcnt, present in CPUs which advertize it under CPUID, Function
> 0x0000_0001_ECX[23]. On CPUs which don't support it, we fallback to the
> default lib/hweight.c sw versions.
>
> A synthetic benchmark comparing popcnt with __sw_hweight64 showed almost
> a 3x speedup on a F10h machine.
>
> Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
OK, this patch looks pretty good now, but I'm completely lost as to what
the baseline of this patch is supposed to be.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2010-02-26 5:34 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
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2010-02-12 19:05 ` [PATCH 2/5] bitops: compile time optimization for hweight_long(CONSTANT) H. Peter Anvin
2010-02-17 13:57 ` Michal Marek
2010-02-17 17:20 ` Borislav Petkov
2010-02-17 17:31 ` Michal Marek
2010-02-17 17:34 ` Borislav Petkov
2010-02-17 17:39 ` Michal Marek
2010-02-18 6:19 ` Borislav Petkov
2010-02-19 14:22 ` [PATCH] x86: Add optimized popcnt variants Borislav Petkov
2010-02-19 16:06 ` H. Peter Anvin
2010-02-19 16:45 ` Borislav Petkov
2010-02-19 16:53 ` H. Peter Anvin
2010-02-22 14:17 ` Borislav Petkov
2010-02-22 17:21 ` H. Peter Anvin
2010-02-22 18:49 ` Borislav Petkov
2010-02-22 19:55 ` H. Peter Anvin
2010-02-23 6:37 ` Borislav Petkov
2010-02-23 15:58 ` Borislav Petkov
2010-02-23 17:34 ` H. Peter Anvin
2010-02-23 17:54 ` Borislav Petkov
2010-02-23 18:17 ` H. Peter Anvin
2010-02-23 19:06 ` Borislav Petkov
2010-02-26 5:27 ` H. Peter Anvin [this message]
2010-02-26 7:47 ` Borislav Petkov
2010-02-26 17:48 ` H. Peter Anvin
2010-02-27 8:28 ` Borislav Petkov
2010-02-27 20:00 ` H. Peter Anvin
2010-03-09 15:36 ` Borislav Petkov
2010-03-09 15:50 ` Peter Zijlstra
2010-03-09 16:23 ` Borislav Petkov
2010-03-09 16:32 ` Peter Zijlstra
2010-03-09 17:32 ` Borislav Petkov
2010-03-09 17:37 ` Peter Zijlstra
2010-03-18 11:17 ` Borislav Petkov
2010-03-18 11:19 ` [PATCH 1/2] bitops: Optimize hweight() by making use of compile-time evaluation Borislav Petkov
2010-03-18 11:20 ` [PATCH 2/2] x86: Add optimized popcnt variants Borislav Petkov
2010-02-18 10:51 ` [PATCH 2/5] bitops: compile time optimization for hweight_long(CONSTANT) Peter Zijlstra
2010-02-18 11:51 ` Borislav Petkov
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