[Samba] 32 seconds vs 72 minutes -- expected performance difference?
Aurélien Aptel
aaptel at suse.com
Thu Feb 21 18:56:34 UTC 2019
Saurabh Nanda <saurabhnanda at gmail.com> writes:
> Help in analysing the tcpdump to get to the bottom of this perf issue would
> be appreciated.
I've looked at the trace but didn't find anything out of the
ordinary. The "STATUS_NO_MORE_FILES" is erroneously taken into account
in the stats because your kernel is missing this patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8e6e72aeceaa
So another red herring I'm afraid :(
Looking at the Service Response Time (SRT, time between request &
response) stat in wireshark we see this:
SMB2 SRT Statistics:
Filter: smb2.cmd
Index Commands Calls Min SRT Max SRT Avg SRT Sum SRT
5 Create 14759 0.000387 0.035268 0.001288 19.003702
6 Close 14713 0.000253 0.029454 0.000629 9.260241
14 Find 27468 0.000237 0.035798 0.000678 18.634827
16 GetInfo 983 0.000276 0.020349 0.000553 0.543487
The way SMB works, you call Create() to open the directory, then call
Find() repeatedly on the handle you get to list its content, then
Close().
In your trace each Create operation takes about 0.0013s on average,
which I can't really say if it's excessive but its taking a lot of the
capture length when you sum them all (19s out of the minute-long trace
you sent).
You should look on the server side maybe, in the logs (try to raise "log
level" in your smb.conf). I'm less knowledgeable on samba perf tweaks
though so hopefully someone else will shine some light.
Cheers,
--
Aurélien Aptel / SUSE Labs Samba Team
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