KIO SMB slave performance issue. Any help?
Albert Astals Cid
aacid at kde.org
Mon May 25 20:58:24 BST 2015
El Dilluns, 25 de maig de 2015, a les 20:32:52, Mark Gaiser va escriure:
> A few days ago i started profiling and debugging the KIO SMB slave to
> figure out why a simple task as listing a directory (in dolphin) is so
> utterly slow. It's been like that for as long as i remember but never had
> attempted to debug it before.
> Do this for example:
> Mount a samba network share locally like so:
> mount -t cifs //path/to/your/share /path/to/your/mount/ -o user=guest,guest
> Now if you browse that folder in dolphin (the cifs mount) you get perfectly
> fine performance. Listings work rapidly.
> If you browse to the exact same location using smb://path/to/your/share
> you're welcomed by notably slower performance. I'm not talking about 0.1
> second vs 0.2, but rather numbers like ~1 second for cifs and ~5 seconds
> for smb://.. You - as a user - will notice that difference.
> I know, i can just use cifs and be done with it. But i prefer to have a
> good smb slave so i rather investigate this further.
> I've tried various things to profile this but i'm stuck.. I did make some
> network profiles (using wireshark) to inspect the smb network packets.The
> big difference i see there is that smb:// sends an ACK for everything it
> receives. CIFS never sends any ACK (that i could find).
> I've tried putting valgrind over it with callgrind and that turned up one
> weird behavior in listing a folder. Every single file request is being send
> through SMBSlave::auth_smbc_get_data which in turn does "if (
> !checkCachedAuthentication( info ) )" which is a quite slow call! But
> disabling that line (you can find it in kio_smb_auth.cpp line 100) doesn't
> speed up directory listing notable. So while that is slow, that is not the
> cause nor the fix.
> Starting a slave in debug mode and attaching a debugger to it also didn't
> tell me anything useful either.
> I have no clue how to investigate this issue further. Would anyone
> (preferably with knowledge of the SMB slave) be kind enough to provide some
> help or pointers where i can find help to tackle this issue?
Have you tried smb command line utils like smbclient? Are they also slow or
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