[Samba] Samba Variables and TCP/IP Throughput

[Greg Dickie]

I believe samba just does setsockopt or ioctl on the sockets. Do you get any 
errors on the interfaces in jumbo? Does your switch support jumbo? Setting 
"use sendfile=yes" will help alot on read speeds from samba. On the windows 
side check the settings. I think the e1000 has some adaptive spacing setting 
that kills throughput. Also some things to check on the linux side. e1000 
module options like rxIntDelay, etc.

You will not get much more performance out of jumbo unless your CPUs are maxed 
but you should not get less. What kind of numbers are you seeing? 


hope this helps.
Greg


On Wednesday 17 December 2003 08:23 am, AndyLiebman at aol.com wrote:
> Thanks for the reply. Do you know (and if so, caan you tell me) what the
> relationship is between these Samba settings and Linux settings such as
> net.core.rmem_default (or _max), net.core.wmem_default (or _max),
> net.ipv4.tcp_rmem and net.ipv4.tcp_wmem.  Do the Samba options override the
> Linux socket options, or do they act as another layer of limits and
> buffers?
>
> Perhaps your TCP window is too small
> You should try the following global settings:
>
>     read size = 65535
>     max xmit = 65535
>     socket options = TCP_NODELAY SO_SNDBUF=65535 SO_RCVBUF=65535
>
>
> Rgds Per
>
> AndyLiebman at aol.com wrote:
> > Hi,
> >
> > I am trying to optimize my gigabit network. I have two Intel 1000 MT
> > Gigabit Server Adapters, which support Jumbo Frames -- as well as a
> > Switch that supports Jumbo Frames. However, I am observing some strange
> > behavior in my
>
> file
>
> > transfers from Windows XP to Linux and I am wondering if it has anything
> > to
>
> do
>
> > with the way the Samba variables are set on my Linux box?
> >
> > The "strange behavior" is that when I set both NICs to use Jumbo Frames
> > [MTU=9014 on the Windows side (includes IP headers) , 9000 on the Linux
> > side (doesn't include the headers], I am getting about half the
> > throughput that
>
> I get
>
> > when I set both NICs to use the standard MTU of 1514/1500. I see the same
> > behavior even if I take the switch out of the system and connect the
>
> Windows XP and
>
> > Linux machines directly to each other (crossover cable not required for
> > computer-to-computer connection with these NICs -- and by the way all of
> > my
>
> cables
>
> > are CAT6).
> >
> > On the Linux side, I am using Samba 3.0.0 on Mandrake Linux 9.2 with all
> > of Mandrake's current updates -- kernel = 2.4.22-21enterprisemdk. The
> > Linux machine is a P4-3.06 Ghz with 1 GB of RAM -- running in
> > hyperthreading mode.
> >
> > I am wondering if any of the Samba socket options settings like
> > tcp_nodelay, so_sndbuf=8192 or so_rcvbuf=8192 are affecting my throughput
> > -- particularly when I am using Jumbo Frames? And are there any other
> > Samba settings that
>
> might
>
> > be interacting in a negative way with my TCP/IP and NIC driver settings
> > that are causing me to get lower throughput with Jumbo Frames instead of
> > higher throughput (which is what I am told I should be getting).
> >
> > Any guidance would be appreciated. I have purchased "The Official Samba 3
> > HOW-TO and Reference Guide" but it really isn't very helpful when it
> > comes
>
> to
>
> > understanding how to tune these options and how various socket options
>
> settings
>
> > interact with other network settings and hardware.
> >
> > Andy Liebman
> > Resolute Films
> > 119 Braintree Street, Suite 410
> > Boston, MA 02134
> >
> > Tel: 617-782-0479
> > Cell: 617-308-0488
> > Fax: 617-782-1071
> > --
> > To unsubscribe from this list go to the following URL and read the
> > instructions:  http://lists.samba.org/mailman/listinfo/samba

-- 
Greg Dickie
just a guy
Maximum Throughput