Samba performance / zero-copy network I/O

From: Gord R. Lamb (
Date: Wed Feb 14 2001 - 15:14:19 EST

Hi everyone,

I'm trying to optimize a box for samba file serving (just contiguous block
I/O for the moment), and I've now got both CPUs maxxed out with system

(For background info, the system is a 2x933 Intel, 1gb system memory,
133mhz FSB, 1gbit 64bit/66mhz FC card, 2x 1gbit 64/66 etherexpress boards
in etherchannel bond, running linux-2.4.1+smptimers+zero-copy+lowlatency)

CPU states typically look something like this:

CPU states: 3.6% user, 94.5% system, 0.0% nice, 1.9% idle

.. with the 3 smbd processes each drawing around 50-75% (according to

When reading the profiler results, the largest consuming kernel (calls?)
are file_read_actor and csum_partial_copy_generic, by a longshot (about
70% and 20% respectively).

Presumably, the csum_partial_copy_generic should be eliminated (or at
least reduced) by David Miller's zerocopy patch, right? Or am I
misunderstanding this completely? :)


- Gord R. Lamb (

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This archive was generated by hypermail 2b29 : Thu Feb 15 2001 - 21:00:25 EST