Re: Samba performance / zero-copy network I/O

From: Jeremy Jackson (
Date: Wed Feb 14 2001 - 15:42:34 EST

"Gord R. Lamb" wrote:

> 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
> load.
> (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
> top).
> 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? :)

I only know enough to be dangerous here, but I believe you will need to
be using one of the network cards whose driver actually uses the
zero-copy patches, and/or which can perform tcp checksum in hardware
(of the network card).

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