Re: [NFS] Re: [PATCH] zerocopy NFS for 2.5.36

From: Andrew Theurer (
Date: Wed Oct 16 2002 - 21:03:33 EST

> From: Neil Brown <>
> Date: Wed, 16 Oct 2002 13:44:04 +1000
> Presumably on a sufficiently large SMP machine that this became an
> issue, there would be multiple NICs. Maybe it would make sense to
> have one udp socket for each NIC. Would that make sense? or work?
> It feels to me to be cleaner than one for each CPU.
> Doesn't make much sense.
> Usually we are talking via one IP address, and thus over
> one device. It could be using multiple NICs via BONDING,
> but that would be transparent to anything at the socket
> level.
> Really, I think there is real value to making the socket
> per-cpu even on a 2 or 4 way system.

I am still seeing some sort of problem on an 8 way (hyperthreaded 8
logical/4 physical) on UDP with these patches. I cannot get more than 2
NFSd threads in a run state at one time. TCP usually has 8 or more. The
test involves 40 100Mbit clients reading a 200 MB file on one server (4
acenic adapters) in cache. I am fighting some other issues at the moment
(acpi wierdness), but so far before the patches, 82 MB/sec for NFSv2,UDP and
138 MB/sec for NFSv2,TCP. With the patches, 115 MB/sec for NFSv2,UDP and
181 MB/sec for NFSv2,TCP. One CPU is maxed due to acpi int storm, so I
think the results will get better. I'm not sure what other lock or
contention point this is hitting on UDP. If there is anything I can do to
help, please let me know, thanks.

Andrew Theurer

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