[Samba] Windows explorer pop-up descriptions: unfair to Samba

[Jeremy Allison]

On Wed, May 27, 2015 at 02:42:00PM -0700, Chris Stankevitz wrote:
> Hello,
> 
> I would like to get this question answered in support of a decision
> about whether or not to move some large shares from Windows Server to
> Samba.
> 
> Windows Explorer has a feature called "Show pop-up description for
> folder and desktop items", which I will call SPD.  SPD, which is
> enabled by default, shows a folder's contents and size when you hover
> your mouse cursor over it.  It even works when you are just moving
> your mouse cursor from the bottom of your screen to the top and just
> "happen" to have it glide across a directory or two.
> 
> Explorer accomplishes SPD by opening the directory and looking at its
> contents in the background.  When the entire contents (including sub
> directories) have been traversed, it creates a pop-up near the
> directory icon.  When browsing network shares, this can generate a lot
> of SMB traffic (depending on directory tree size).  This can also take
> a long time to complete.  You can use wireshark to watch tens of
> thousands of smbd_dirptr_get_entry messages generated by this activity
> in large shares.
> 
> Question: What does SPD do if the user "hovered" his cursor over a
> directory, but only momentarily, before moving this mouse elsewhere on
> the screen (on a network share)?
> 
> Answer when connected to a samba server: When the user momentarily
> hovered his cursor over the directory, explorer begins recursing the
> directory structure,s ending and receiving SMB commands.  Even after
> the user moves his mouse away, this recursion continues and can take
> minutes to complete (imagine a very large directory structure).
> Frighteningly, sometimes (but not always), Explorer.exe locks up
> waiting for this process to complete.  During the "lock up", the user
> experiences an hourglass/spinning_blue_wheel and the explorer window
> does not refresh.
> 
> Question: Why does it seem like this undesirable "lock up" happens
> only when connected to a Samba server and not when connected to a
> genuine Windows Server?
> 
> Answer: ?

Don't know. Can you upload a comparison wireshark trace from
this being done against a Windows server and being done against
a Samba server so we have a chance of answering this question ?