Re: Kernel 3.0: Instant kernel crash when mounting CIFS (also crasheswith linux-3.1-rc2

From: Justin Piszcz
Date: Thu Aug 18 2011 - 14:54:08 EST




On Thu, 18 Aug 2011, Jeff Layton wrote:

On Thu, 18 Aug 2011 14:18:15 -0400 (EDT)
Justin Piszcz <jpiszcz@xxxxxxxxxxxxxxx> wrote:



Like I said, read performance with cifs.ko just plain sucks currently.

Don't look for cifs.ko to achieve anywhere near NFS' performance unless
you jump through some very odd hoops (like multithreading your workload
in userspace, etc). cifs.ko just doesn't do a good job of keeping the
pipe "stuffed" as most calls are handled synchronously. A single task
can only handle one call on the wire in most cases. The exception here
is writes, but that just recently changed...

Reads are done using relatively small buffers and then copied to
pagecache. Part of what I'm working on will be to allow for much larger
reads directly into the pagecache. That should also help performance
significantly.


Jeff,

Understood, thank you for the help thus far and the patch to stop the crashing
kernel problem, it is much appreciated, I'll look forward to the new patch sets
to improve the performance of CIFS mounts.

Justin.


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