1KB SMB packet size killing throughput (XP to Ubuntu)

Raghu A raghua1111+nabble at gmail.com
Wed Jun 24 13:19:32 MDT 2009

am investigating (and looking for help for) very low transfer rate from XP
client to Ubuntu samba server.
More details are at

gist : write is getting only 1-1.5MB/s over ethernet.

The main culprit seems to be 1KB SMB packet. tcpdump and strace show XP
sends only 1KB each time.  I don't have enough knowledge to know whether
this is a symptom, cause, or a side effect of the real problem.

There are couple of other strange issues on actual data consumption by smbd

XP client :  netstat on server shows "1092" bytes many times in receive
buffers, indicating server is not consuming the data fast enough.
Ubuntu client : Though the transfer is twice as fast, I almost never notice
data on receive buffer. indicating smbd is consuming data faster than sent
by client.

Is XP client making smbd work more?

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