[Samba] Performance regression of Windows clients?

Giuseppe Lo Presti Giuseppe.LoPresti at cern.ch
Mon Oct 19 07:00:54 UTC 2020

On 15/10/2020 11:15, Ralph Boehme wrote:
> Am 10/15/20 um 11:01 AM schrieb Giuseppe Lo Presti:
>> For the reproducibility, it should be fairly straightforward with a
>> Powershell script as posted at the bottom, and either simply strace smbd
>> (just count how many accesses are executed per file), or use wireshark
>> as it understands the SMB protocol. Then compare this with the same
>> actions performed via bash over a CIFS-mounted path.
> fwiw, be careful using Powershell scripts trying to reproduce Windows
> Explorer behaviour as both will behave differently -- sometimes grossly.

Thank you for the heads-up.

Indeed I confirm that Windows Explorer behaves differently, in that less 
of those SMB2_FIND_ID_BOTH_DIRECTORY_INFO queries are issued (e.g. on 
delete of many files). Nevertheless, I confirm a large amount of 
metadata-related requests (stat fstatat, listxattr, getxattr) from 
Windows GUIs, which are not present with Linux clients.

Given the state of affairs, I guess we'll have to really make sure we 
can cache a lot more metadata than required, whereas optimizing the 
Windows clients side does not appear to be at all possible.


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