samba - Oct 2010 - Diagnosing Performance Issues

Hi All,

First off my apologies if this is the wrong place to be asking.

I seem to have a problem where the smbd process is using a massive 
amount of CPU for network transfers. It averages about 70-90% usage on 
both cores of a dual-core machine when transferring between disks (or 
over the network) using samba/cifs shares.

Along with this I also notice the transfers going from a steady 
30-40mb/sec to anywhere from 1-4MB/sec. It seems to resolve itself then 
re-occur multiple times during a transfer. I have tried tweaking buffer 
settings and the like with no success.

iostat shows corresponding transfer rates that match what Windows is 
reporting for transfer speeds.

Any ideas where I can start looking? I've done a fair bit of looking, 
but I'm not quite ready to say it's a hardware problem just yet.

Cheers :)

On Mon, Oct 04, 2010 at 01:21:39PM +0800, Shane Arnold
wrote:
> First off my apologies if this is the wrong place to be asking.
> 
> I seem to have a problem where the smbd process is using a massive
> amount of CPU for network transfers. It averages about 70-90% usage
> on both cores of a dual-core machine when transferring between disks
> (or over the network) using samba/cifs shares.
> 
> Along with this I also notice the transfers going from a steady
> 30-40mb/sec to anywhere from 1-4MB/sec. It seems to resolve itself
> then re-occur multiple times during a transfer. I have tried
> tweaking buffer settings and the like with no success.
> 
> iostat shows corresponding transfer rates that match what Windows is
> reporting for transfer speeds.
> 
> Any ideas where I can start looking? I've done a fair bit of
> looking, but I'm not quite ready to say it's a hardware problem
just
> yet.
strace'ing the smbd might be a start...

Volker