From: Andi Kleen <ak@suse.de>
To: Dave Jones <davej@redhat.com>
Cc: alan@lxorguk.ukuu.org.uk, torvalds@osdl.org,
richard.brunner@amd.com, linux-kernel@vger.kernel.org,
akpm@osdl.org
Subject: Re: [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata
Date: Thu, 11 Sep 2003 16:32:48 +0200 [thread overview]
Message-ID: <20030911163248.15aeaab6.ak@suse.de> (raw)
In-Reply-To: <20030911142809.GB20434@redhat.com>
On Thu, 11 Sep 2003 15:28:09 +0100
Dave Jones <davej@redhat.com> wrote:
> On Thu, Sep 11, 2003 at 04:24:21PM +0200, Andi Kleen wrote:
> > I considered that when writing the patch, but: is_prefetch is a single byte
> > memory access for something already in cache. Checking for an Athlon
> > CPU needs two memory accesses in boot_cpu_data at least (checking vendor
> > and model)
>
> You only need to check it once when the path is first taken, and then
> set a variable that makes you exit as soon as you enter it again.
Checking the variable also an memory access.
is_prefetch does a few more instructions around the memory access, but these
are completely left in the noise.
The is_prefetch check is likely faster even than checking that variable because
the chances that the EIP is already in cache are much higher than some rarely
used variable.
-Andi
next prev parent reply other threads:[~2003-09-11 14:33 UTC|newest]
Thread overview: 123+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-11 0:56 Update on AMD Athlon/Opteron/Athlon64 Prefetch Errata richard.brunner
2003-09-11 1:27 ` [PATCH] 2.6 workaround for Athlon/Opteron prefetch errata Andi Kleen
2003-09-11 1:44 ` Andrew Morton
2003-09-11 1:47 ` Andi Kleen
2003-09-11 14:15 ` Jeff Garzik
2003-09-11 14:26 ` Andi Kleen
2003-09-11 14:34 ` Jeff Garzik
2003-09-11 14:58 ` Andi Kleen
2003-09-11 15:06 ` Jeff Garzik
2003-09-11 20:08 ` bill davidsen
2003-09-11 19:56 ` bill davidsen
2003-09-11 20:44 ` Alan Cox
2003-09-11 21:29 ` Mike Fedyk
2003-09-11 21:38 ` bill davidsen
2003-09-12 17:32 ` Eric W. Biederman
2003-09-12 17:56 ` Andi Kleen
2003-09-12 17:59 ` Jeff Garzik
2003-09-12 18:22 ` Adrian Bunk
2003-09-12 18:28 ` Andi Kleen
2003-09-12 18:39 ` Jeff Garzik
2003-09-12 18:45 ` Jeff Garzik
2003-09-12 18:48 ` Adrian Bunk
2003-09-12 19:07 ` Andi Kleen
2003-09-12 19:05 ` Martin Schlemmer
2003-09-12 19:30 ` Andi Kleen
2003-09-12 19:58 ` Martin Schlemmer
2003-09-12 20:00 ` Adrian Bunk
2003-09-15 0:15 ` bill davidsen
2003-09-14 23:51 ` bill davidsen
2003-09-14 23:49 ` bill davidsen
2003-09-14 23:47 ` bill davidsen
2003-09-15 1:02 ` Zwane Mwaikambo
2003-09-15 2:08 ` Nick Piggin
2003-09-15 3:55 ` Bill Davidsen
2003-09-15 7:45 ` Alan Cox
2003-09-15 12:11 ` Bill Davidsen
2003-09-15 13:48 ` Alan Cox
2003-09-15 18:50 ` Bill Davidsen
2003-09-12 18:03 ` Mike Fedyk
2003-09-11 13:54 ` Linus Torvalds
2003-09-11 14:01 ` Andi Kleen
2003-09-11 14:14 ` Dave Jones
2003-09-11 14:29 ` Andi Kleen
2003-09-11 14:14 ` Alan Cox
2003-09-11 14:24 ` Andi Kleen
2003-09-11 14:28 ` Dave Jones
2003-09-11 14:32 ` Andi Kleen [this message]
2003-09-11 20:14 ` bill davidsen
2003-09-11 16:58 ` Jamie Lokier
2003-09-11 17:05 ` Andi Kleen
2003-09-11 17:32 ` Jamie Lokier
2003-09-11 17:39 ` Andi Kleen
2003-09-11 17:48 ` Jamie Lokier
2003-09-11 18:18 ` Andi Kleen
2003-09-11 18:59 ` Jamie Lokier
-- strict thread matches above, loose matches on Subject: below --
2003-09-11 3:43 Nakajima, Jun
2003-09-11 4:03 ` Valdis.Kletnieks
[not found] <uqD5.3BI.3@gated-at.bofh.it>
2003-09-11 4:14 ` Andi Kleen
2003-09-11 4:58 ` dada1
2003-09-11 5:11 ` Andi Kleen
2003-09-11 5:58 ` dada1
2003-09-11 4:55 richard.brunner
2003-09-11 16:55 ` Jamie Lokier
2003-09-12 14:14 ` Martin Schlemmer
2003-09-11 17:09 richard.brunner
2003-09-11 17:14 richard.brunner
2003-09-11 17:17 richard.brunner
2003-09-13 16:54 ` Pavel Machek
2003-09-12 21:24 John Bradford
2003-09-15 6:32 John Bradford
2003-09-15 7:40 ` Alan Cox
2003-09-15 12:02 ` Bill Davidsen
2003-09-15 11:48 ` Bill Davidsen
2003-09-15 20:55 ` Adrian Bunk
2003-09-16 0:26 ` Bill Davidsen
2003-09-15 8:31 John Bradford
2003-09-15 8:32 ` Nick Piggin
2003-09-15 20:51 ` Adrian Bunk
2003-09-15 9:39 John Bradford
2003-09-15 9:58 ` Nick Piggin
2003-09-15 10:54 John Bradford
2003-09-15 10:52 ` Nick Piggin
2003-09-15 13:45 ` Alan Cox
2003-09-15 18:44 ` Bill Davidsen
2003-09-15 11:46 John Bradford
2003-09-15 12:38 ` Nick Piggin
2003-09-15 13:46 ` Chris Meadors
2003-09-15 14:00 ` Nick Piggin
2003-09-16 15:06 ` Bill Davidsen
2003-09-16 15:24 ` Nick Piggin
2003-09-15 12:28 Mikael Pettersson
2003-09-15 18:13 ` Bill Davidsen
2003-09-16 11:54 ` Jamie Lokier
2003-09-15 12:43 John Bradford
2003-09-15 18:21 ` Bill Davidsen
2003-09-15 14:21 John Bradford
2003-09-15 16:21 richard.brunner
2003-09-15 19:15 ` Bill Davidsen
2003-09-16 11:46 ` Jamie Lokier
2003-09-16 13:30 ` Dave Jones
2003-09-16 13:52 ` Bill Davidsen
2003-09-16 15:25 ` Timothy Miller
2003-09-16 16:53 ` Bill Davidsen
2003-09-16 17:22 ` Jamie Lokier
2003-09-16 17:23 ` Jamie Lokier
2003-09-18 7:43 ` Pavel Machek
2003-09-18 14:05 ` Dave Jones
2003-09-18 15:56 ` Jamie Lokier
2003-09-18 17:34 ` Bill Davidsen
[not found] <200309150632.h8F6WnHb000589@81-2-122-30.bradfords.org.uk.suse.lists.linux.kernel>
[not found] ` <1063611650.2674.1.camel@dhcp23.swansea.linux.org.uk.suse.lists.linux.kernel>
2003-09-15 18:29 ` Andi Kleen
2003-09-15 19:19 John Bradford
2003-09-15 19:34 John Bradford
2003-09-15 19:25 ` Bill Davidsen
2003-09-15 22:28 ` Alan Cox
2003-09-15 19:51 richard.brunner
2003-09-16 0:01 ` David Lang
2003-09-16 0:20 ` Bill Davidsen
2003-09-16 11:50 ` Jamie Lokier
2003-09-16 13:46 ` Bill Davidsen
2003-09-16 17:21 ` Jamie Lokier
2003-09-15 20:03 Nakajima, Jun
2003-09-15 20:20 Nakajima, Jun
2003-09-16 2:23 richard.brunner
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