From: Andrew Morton <akpm@osdl.org>
To: Andi Kleen <ak@suse.de>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org, richard.brunner@amd.com
Subject: Re: [PATCH] Athlon/Opteron Prefetch Fix for 2.6.0test5 + numbers
Date: Tue, 16 Sep 2003 19:44:46 -0700 [thread overview]
Message-ID: <20030916194446.030d8e70.akpm@osdl.org> (raw)
In-Reply-To: <20030917022256.GA17624@wotan.suse.de>
Andi Kleen <ak@suse.de> wrote:
>
>
> This is much more efficient than the previous workaround used in the kernel,
> which checked for AMD CPUs in every prefetch(). This can be seen
> in the size of the vmlinux:
That is hardly a serious comparison: the workaround is just to stop the
oopses while this gets sorted out. It makes no pretense at either
efficiency or permanence.
> Without patch:
> text data bss dec hex filename
> 4020232 665956 169092 4855280 4a15f0 vmlinux
> With patch:
> 4011578 665973 169092 4846643 49f433
hrm. Why did data grow?
> With prefetch check: 3.7268 microseconds
> Without prefetch check: 3.65945 microseconds
We don't know how much of this difference is due to removing the branch and
how much is due to reenabling prefetch.
It would be interesting to see comparative benchmarking between prefetch
and no prefetch at all, see whether this feature is worth its icache
footprint.
next prev parent reply other threads:[~2003-09-17 2:44 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-17 2:22 [PATCH] Athlon/Opteron Prefetch Fix for 2.6.0test5 + numbers Andi Kleen
2003-09-17 2:44 ` Andrew Morton [this message]
2003-09-17 3:25 ` Andi Kleen
2003-09-17 4:53 ` Nick Piggin
2003-09-17 5:08 ` Andrew Morton
2003-09-17 5:19 ` Nick Piggin
2003-09-17 7:15 ` Dave Hansen
2003-09-17 5:26 ` Andi Kleen
2003-09-17 5:44 ` Nick Piggin
2003-09-17 19:53 ` Linus Torvalds
2003-09-17 20:21 ` Andi Kleen
2003-09-17 20:50 ` Linus Torvalds
2003-09-17 21:12 ` Andi Kleen
2003-09-18 15:38 ` Jamie Lokier
2003-09-18 16:04 ` Jamie Lokier
2003-09-18 17:06 ` Andi Kleen
2003-09-18 19:48 ` Jamie Lokier
2003-09-19 6:55 ` Kai Henningsen
2003-09-19 10:02 ` Andreas Schwab
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