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Re: File operations really slow in emacs

On 14/02/2012 8:52 AM, Corinna Vinschen wrote:
On Feb 14 08:37, Ryan Johnson wrote:

On 13/02/2012 8:31 AM, Ryan Johnson wrote:
On 11/02/2012 5:11 AM, Corinna Vinschen wrote:
On Feb 10 20:18, Ryan Johnson wrote:
Hi all,

For some reason file operations have become very slow inside emacs
starting yesterday. It's especially painful when saving a file
that's managed by mercurial (more than 20 seconds!), but I've seen
it on the command line as well (x-server takes a similar amount of
time to start, for example). I'm running the latest everything and
I've run rebaseall. I verified that Windows Defender did not
silently re-enable itself since I last disabled it (you can't
actually uninstall it) and no other BLODA are present on my machine.
The problem persists across reboots.

I have vague memories that this has turned up in the past (maybe
12-15 months ago?) but Google isn't turning up anything. Attaching
strace to emacs during the save makes it take a full 35 seconds and
reports the following:

$ cat emacs.strace | awk '{if ($1>   1000000) { print }}' | grep -v
26910790 26912157 [main] emacs-X11 5188 child_copy: dll bss - hp
0x264 low 0x611FC000, high 0x61230770, res 1
1128419 2125655 [main] python2.6 5188 read: read(5, 0x8009DB60,
65536) blocking
25850184 32830582 [main] python2.6 5188 stat_worker: 0 =
   This looks suspicious.  I assume you're suffering from SMB network
is there a workaround? Neither "always run elevated" nor "always
keep all network drives mounted" seems like a reasonable
What are you expecting?  Was my reply in not sufficient?
The reply explains why running elevated avoids the problem -- apparently a side-effect of Windows' user token handling.

It does not explain why it's a good idea to always run elevated to get a side effect that compensates for bad behavior which is arguably a bug (though that's what I'm doing right now for lack of a better option -- I often work off-grid, so I can't always have all network drives mapped).

AFAICT, `stat /cydrive` runs into trouble because it enumerates all drive letters using GetFileAttributes, and only counts local drives as "links" to the "directory" : 2 + ndrives - nfloppies - nnonlocal. This relies on the fact (a side effect?) that GetFileAttributes returns ERROR_BAD_NETPATH for network shares (but apparently only after timing out an attempt to connect disconnected ones). Not sure what happens for USB drives (are they "floppies" ?). Is there no other way to enumerate the local drives, and even if there isn't, does anybody actually care about that particular link count? AFAIK, directory link counts only matter when you want to run fsck (which cygwin doesn't have) or delete a directory. Even if cygwin's rm pays attention to link counts, which I doubt, anyone issuing `rm -rf /cygdrive` has far bigger problems on their hands.


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