From: Andi Kleen <ak@suse.de>
To: Akira Tsukamoto <at541@columbia.edu>
Cc: linux-kernel@vger.kernel.org,
Hirokazu Takahashi <taka@valinux.co.jp>,
Andrew Morton <akpm@digeo.com>,
Denis Vlasenko <vda@port.imtp.ilyichevsk.odessa.ua>,
Andi Kleen <ak@suse.de>
Subject: Re: [CFT][PATCH] 2.5.47 Athlon/Druon, much faster copy_user function
Date: Sat, 16 Nov 2002 11:56:52 +0100 [thread overview]
Message-ID: <20021116115652.A26519@wotan.suse.de> (raw)
In-Reply-To: <20021115235234.8DE4.AT541@columbia.edu>
You don't seem to save/restore the FPU state, so it will be likely
corrupted after your copy runs.
Also I'm pretty sure that using movntq (= forcing destination out of
cache) is not a good strategy for generic copy_from_user(). It may
be a win for the copies in write ( user space -> page cache ), but
will hurt for all the ioctls and other things that actually need the
data in cache afterwards. I am afraid it is not enough to do micro benchmarks
here.
-Andi
next prev parent reply other threads:[~2002-11-16 10:49 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-11-16 6:53 [CFT][PATCH] 2.5.47 Athlon/Druon, much faster copy_user function Akira Tsukamoto
2002-11-16 10:56 ` Andi Kleen [this message]
2002-11-16 18:22 ` Akira Tsukamoto
2002-11-16 18:30 ` Andi Kleen
2002-11-16 18:50 ` Akira Tsukamoto
2002-11-16 22:23 ` Hirokazu Takahashi
2002-11-16 21:55 ` Akira Tsukamoto
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