Poor Samba throughput on 6.0

Bradley W. Dutton brad-fbsd-perf at duttonbros.com
Thu Nov 10 11:03:33 PST 2005

I recently upgraded to gigabit and was expecting faster Samba performance
as well. I don't recall the exact numbers but net.inet.tcp.delayed_ack=0
did help quite a bit on my box.

I too tried mtu (intel cards and SMC jumbo switch) and polling but the
transfer rates would max out around 10megs/sec with Samba. Disk transfer
rate shouldn't be a problem, the disk easily does 20+meg/sec writes.  ttcp
transfer rates are 30+ megs/sec. One thing I did notice with ttcp is that
using the -D option (TCP_NODELAY?) helped a lot.

I'm using a freebsd/samba 6.0 server and windows xp clients.  I'll test
the other 2 sysctls over the next few days to see if they help.


> 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

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