cvs commit: src/sys/kern kern_descrip.c

Jeff Roberson jroberson at
Wed Jul 25 00:44:01 UTC 2007

On Tue, 24 Jul 2007, Jeremie Le Hen wrote:

> On Mon, Jul 23, 2007 at 05:38:35PM -0700, Julian Elischer wrote:
>>  I think that is the wrong question..
>>  the question is "why do we drop off after 8?"
>>  which I'm sure Jeff is already working on.
> Actually since the workbench has been run on an 8-core amd64 and that
> both Linux and FreeBSD drop here, I thought it was natural to get the
> best performance with 8 threads...  Am I wrong?

Well there seem to be some significant periods of waittime that are purely 
within mysql.  I do not understand these very well but I do not think that 
all of the dropoff after 8 threads is our fault.

There is, however, some considerable contention reported.  My select patch 
was created to address this.  Attilio's lockmgr work should fix the next 
biggest bottleneck.  After that it looks like filedescriptor locking needs 
some more attention since there are so many threads with a shared fd set.


> Regards,
> -- 
> Jeremie Le Hen
> < jeremie at le-hen dot org >< ttz at chchile dot org >

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