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

David Collier-Brown davec-b at rogers.com
Sun Jan 2 16:44:51 GMT 2005

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...

--dave (mostly a solaris guy) c-b

> net:
> Marvell Gigabit Ethernet 32bit PCI NICs, using 9K jumbograms
> capable of doing about 720 Mbps bandwith for TCP application
> (meassured with netperf after link layer tuning).
> OS:
> FreeBSD 5-STABLE (Dec 19 20:48:37)

David Collier-Brown,         | Always do right. This will gratify
System Programmer and Author | some people and astonish the rest
davecb at spamcop.net           |                      -- Mark Twain

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