From: Andi Kleen <andi@firstfloor.org>
To: "Ma, Ling" <ling.ma@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>, "mingo@elte.hu" <mingo@elte.hu>,
"hpa@zytor.com" <hpa@zytor.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register
Date: Fri, 12 Oct 2012 15:35:54 +0200 [thread overview]
Message-ID: <20121012133554.GA16230@one.firstfloor.org> (raw)
In-Reply-To: <B2310DA9850C8743AA7AA0055500E90F0FD709C4@SHSMSX102.ccr.corp.intel.com>
> I tested new and original version on core2, the patch improved performance about 9%,
That's not useful because core2 doesn't use this variant, it uses the
rep string variant. Primary user is P4.
> Although core2 is out-of-order pipeline and weaken instruction sequence requirement,
> because of ROB size limitation, new patch issues write operation earlier and
> get more parallelism possibility for the pair of write and load ops and better result.
> Attached core2-cpu-info (I have no older machine)
If you can't test the CPUs who run this code I think it's safer if you
add a new variant for Atom, not change the existing well tested code.
Otherwise you risk performance regressions on these older CPUs.
-Andi
--
ak@linux.intel.com -- Speaking for myself only.
next prev parent reply other threads:[~2012-10-12 13:36 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 12:29 [PATCH RFC 2/2] [x86] Optimize copy_page by re-arranging instruction sequence and saving register ling.ma
2012-10-11 13:40 ` Andi Kleen
2012-10-12 3:10 ` Ma, Ling
2012-10-12 13:35 ` Andi Kleen [this message]
2012-10-12 14:54 ` Ma, Ling
2012-10-12 15:14 ` Andi Kleen
2012-10-11 14:35 ` Konrad Rzeszutek Wilk
2012-10-12 3:37 ` Ma, Ling
2012-10-12 6:18 ` Borislav Petkov
2012-10-12 9:07 ` Ma, Ling
2012-10-12 18:04 ` Borislav Petkov
2012-10-14 10:58 ` Borislav Petkov
2012-10-15 5:00 ` Ma, Ling
2012-10-15 5:13 ` George Spelvin
-- strict thread matches above, loose matches on Subject: below --
2012-10-12 21:02 George Spelvin
2012-10-12 23:17 ` Borislav Petkov
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