From: Andi Kleen <ak@suse.de>
To: Nivedita Singhvi <niv@us.ibm.com>
Cc: linux-kernel@vger.kernel.org, rwhron@earthlink.net
Subject: Re: [lmbench] tcp bandwidth on athlon
Date: 21 Jul 2002 21:30:51 +0200 [thread overview]
Message-ID: <p73lm84ubdg.fsf@oldwotan.suse.de> (raw)
In-Reply-To: Nivedita Singhvi's message of "21 Jul 2002 21:21:07 +0200"
Nivedita Singhvi <niv@us.ibm.com> writes:
> Hmm, so if K6 and Xeon can scrounge up 80% of pipe
> performance, why is the Athlon an order of magnitude off
> at 8%? How did your Athlon perform in other tests relative
> to these other procs?
The pipe test basically tests copy_from_user()/copy_to_user().
The standard implementation of these macros (essentially rep ; movsl)
doesn't exploit the Athlon very well - it is not good at this
instruction. AFAIK Intel CPUs have an faster microcode
implementation for this.
You could likely do better on Athlon with a copy*user that uses
an unrolled loop with explicit movls or even SSE.
[similar to the implementation the x86-64 port uses, but without
the NT instructions]
-Andi
next parent reply other threads:[~2002-07-21 19:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1027279106.3d3b0902a9209@imap.linux.ibm.com.suse.lists.linux.kernel>
2002-07-21 19:30 ` Andi Kleen [this message]
2002-07-22 22:39 [lmbench] tcp bandwidth on athlon rwhron
-- strict thread matches above, loose matches on Subject: below --
2002-07-21 19:18 Nivedita Singhvi
2002-07-21 13:21 rwhron
2002-07-21 16:44 ` Alan Cox
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