Poor Samba throughput on 6.0

Joao Barros joao.barros at gmail.com
Thu Nov 10 11:08:27 PST 2005


On 11/10/05, Robert Watson <rwatson at freebsd.org> wrote:
> On Wed, 9 Nov 2005, Mike Jakubik wrote:
>
> > I have done many tests to try to determine the poor performance on my
> > systems (FreeBSD-current connected directly to Windows XP via identical
> > Intel Pro 1000 cards) and my only conclusion is that Samba on FreeBSD
> > when talking to a Windows box is simply fubared. Im willing to bet thats
> > not the case on Linux. I can get great speeds (~30MB/s) using ftp
> > between the machines, but when i use Samba, i get a maximum of 11MB/s. I
> > have tried playing with mtu size, samba options, polling, but there does
> > not seem to be any visible bottlenecks, its just simply slow. It would
> > be great if someone could get to the bottom of this, its quite
> > frustrating.
>
> There are a number of TCP related configuration frobs on FreeBSD.  It
> would be quite interesting to know how modifying each of the following
> settings affects Samba performance:
>
> net.inet.tcp.delayed_ack
> net.inet.tcp.sack.enable
> net.inet.tcp.inflight.enable
>
> There has been recent evidence that the inflight bandwidth calculation is
> having problems generating stable performance at high bandwidth and low
> latency, so I might try that one first.
>
> Robert N M Watson

I just tested on my home machine and delayed_ack and sack.enable have
little or no effect on the results.
inflight.enable on the other hand had a huge impact! With the file
cached I've gone from flat 5.5MB/s up to also flat 7.2MB/s
It's an improvement but there is still a difference up to those
theoretical 12.5MB/s on a 100mbit link
--
Joao Barros


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