Re: [Lse-tech] efficient copy_to_user and copy_from_user routines in Linux Kernel

From: Niels Christiansen (
Date: Mon Jun 24 2002 - 15:24:46 EST


As you may recall, I showed you results back in February with MMX registers
enabled. I also gave you a simple patch to test activate the use of the MMX
registers. It would be interesting if you could run your test with the MMX
patch so we could see the difference. In case you forgot the patch, it is
as simple as setting CONFIG_X86_USE_3DNOW on for Pentium III in

Niels Christiansen

----- Original Message -----
From: "Mala Anand" <>
To: "Linux Kernel Mailing List" <>;
Sent: Monday, June 24, 2002 2:34 PM
Subject: [Lse-tech] efficient copy_to_user and copy_from_user routines in
Linux Kernel

> Here is a 2.5.19 patch that improves the performance of IA32 copy_to_user
> and copy_from_user routines used by :
> (1) tcpip protocol stack
> (2) file systems
> Badari Pulavarty has suggested using mmx registers instead of integer
> registers in the unrolled loop copy method. We are both investigating
> the performance of the copy routines when the mmx registers are used.
> Regards,
> Mala

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