[Samba] 32 seconds vs 72 minutes -- expected performance difference?

Nick Howitt nick at howitts.co.uk
Sat Feb 16 09:13:50 UTC 2019

On 16/02/2019 02:43, Saurabh Nanda via samba wrote:
>>> 2) Is this normal -- fs/cifs/smb2misc.c: Calculated size 157 length 156
>>> mismatch mid 11907
>> Could be a bug or miscalculated length + non critical warning, I also
>> see this on master kernel. Either way I doubt it's slowing everything down.
> Should I file a bug for this?
>> ## OPERATION 1 -  `ls debug.log` -- simply listing a single file. Does
>>> anything seem wrong with this?
>> This is going to be disapointing but we don't see the error that gets
>> added in the stats in this log extract. Have you checked your samba logs
>> as well? There might be useful information in there (might have to
>> increase "log level" in smb.conf, it can go up to 10 but that will
>> generate a *lot* of data).
>> If you still don't want to share the network capture you should at least
>> try to open it yourself in wireshark, it would save everyone time.
> I tried looking at the network capture using `tcpdump -A -X` but wasn't
> able to understand anything. I tried installing wireshark on a throwaway
> cloud instance, but realised that it's a GUI program. Can you please help
> be with the network trace at
> https://www.dropbox.com/s/r8cn0qggrvmrpc3/dump.pcap?dl=0 ? It's capturing
> the network chatter for ~1min of `ls -lR` on the shared folder. Does this
> help in getting to the bottom of this problem?
>> Also, please attach files or disable word-wrapping when you send logs in
>> the future.
> Ah - I thought most mailing lists scrub attachments.
> -- Saurabh.
This is a complete lateral jump. In the El/Centos line of distros I've 
seen a lot of issues caused by using the r8169 driver on 
RTL8111/8168/8411 cards including things like DNS failures and network 
slowdowns and other more exotic issues. The card performs better (in 
EL/Centos) with the r8168 driver which does not come built into the 
kernel, unless Ubuntu has unified the two drivers under the r8169 
banner. You can do a quick check with:
lspci -k | grep Eth -A 3

Please ignore this post if it is totally irrelevant.


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