Speed problem - smbclient doesn't send duplicate ACKs in case of pacekt loss

Christopher R. Hertel crh at ubiqx.mn.org
Mon Jan 3 19:08:50 GMT 2005

On Sun, Jan 02, 2005 at 11:44:51AM -0500, David Collier-Brown wrote:
> Heinz Knocke wrote:
> [...] currently work on tcp tuning especially for gigabit ethernet 
> purposes. 
> >So, I'm trying to tune samba on my two directly linked boxes and
> >encountered a strange problem.
> >When serving one big (1-2GB file) locally over lo0 transmission
> >reaches speed of about 32 MB/s which is OK.  But when doing the very
> >same thing over the network, speed drops to 10 MB/s. It's so because
> >of quite often single packet drops, which are detected by the server
> >only using RTO timeout. 
>  That sounds genuinely odd!  Samba proper doesn't work at that low
> a level, and you already tested with netperf, so I suspect it's
> an interaction between Samba and the OS, possibly down at the
> netbios/netbuei level...

Samba in general and smbclient in particular don't have a netbios/netbeui
level.  All of the NBT mapping is done as the packets are built.  This is
done in user space, before handing them to the socket for transport.

Chris -)-----

"Implementing CIFS - the Common Internet FileSystem" ISBN: 013047116X
Samba Team -- http://www.samba.org/     -)-----   Christopher R. Hertel
jCIFS Team -- http://jcifs.samba.org/   -)-----   ubiqx development, uninq.
ubiqx Team -- http://www.ubiqx.org/     -)-----   crh at ubiqx.mn.org
OnLineBook -- http://ubiqx.org/cifs/    -)-----   crh at ubiqx.org

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