Performance issue with Samba 3-0

[Ravi Wijayaratne]

Hi All,

We are seeing a performance degradation of Samba 3.0 with Linux 2.4.19-xfs-1.2 (Case A) compared
to
Linux 2.4.19-XFS-1.1 (Case B). The details are as follows.

1. We are seeing a ~15% drop in netbench performance (Clients were a mix of NT/2k) performance.
Upon examining the detailed results we see that write operations are hurting 
overall performance
2. From profiling information we see that for Case A there were 500000 more SMB PDUs (roughly
about 20-25%) used for the test. The discrepancy was for the most part accounted 
for by the elevated number of trans2_query_filepath_info PDUs  and the WriteX PDus.

3. we examined the debug level 10 logs. We see that for Case A the WriteX op sequence is 
WriteX->qfilepathinfo->writeX->qfilepathinfo->writeX....
but for Case B is
WriteX->WriteX->WriteX .....

So it seems that for *identical Samba 3.0 builds* the clients chose a different write protocol
for Case A which was counter productive. 

I am curious what could have caused this.?

Some insight is much appreciated.

Ravi
  

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Ravi Wijayaratne

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