On 6/28/2012 11:31 PM, Jeffrey Altman wrote:
On 6/28/2012 4:21 PM, Douglas E. Engert wrote:
The best I can tell, Thunderbird for the local mail folders is doing
synchronous writes, which is another performance problem in itself,
SysInternals Process Monitor will tell you exactly what thunderbird.exe
is doing.
Yes, I have been doing that.
Using 1.7.1100, the TB "Move To" of a 3.8MB mail message with an excel
attachment, I see some 49,000 writes of 74 bytes that take more then 0.001
seconds each. These writes account for 91% of the data and at best 0.001
seconds each account for at least 49 seconds of the 60 seconds to copy
the file.
If TB buffers the output using an 8K buffer, its more like 490 writes,
and the copy takes less then 2 second (by my watch) which is acceptable.
So the overhead appears to be in the write operations and not in the
amount of data.
So even though the writes/second is about 819, the big problem is
Thunderbird's not buffering the data.
(I have not tried writing a test program to write out 3.8MB of data
at 74 bytes each, to see if there may be still be some other Thunderbird
issues. I can't do anything on this next week, but will try the week after.)
although it looks like a Delete/Copy/Move has its own thread (or its using
the main thread which might be way it is not responding) but as
a user, deleting messages (that get copied to the Trash folder)
it becomes single threaded waiting on the Trash folder and I have to wait
to do the next delete.
Note that by buffering I get about 60 times improvement in throughput,
so the performance hit is caused more by the number of writes, not on how
much data is written.
That makes sense because for each write an extent exchange with the
afsd_service is going to take place.
Could Windows be doing some throttling based on the number of writes?
Unlikely.
I don't get this bad of performance using the Windows DFS as I do AFS.
DFS only uses the Windows page cache. It doesn't have a cache of its own.
CPU time, I/O and network I/O are NOT maxed out during one of these
Delete operations.
I wouldn't expect them to be. Thunderbird is serializing one request at
a time.
There are many things that could be done to further improve performance
in the extent management interfaces. However, my focus has been on
application compatibility and stability. Those are the areas which the
small number of organizations contributing to Windows client development
consider to be the priority.
Understand.
Jeffrey Altman
--
Douglas E. Engert <[email protected]>
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
(630) 252-5444
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