[Fwd: Re: Mysql - Linuxthreads : Still needed?]

[Robert Watson]

On Wed, 10 Nov 2004, Julian Elischer wrote:

> send to the right list. 

So, the good news is that we've successfully dramatically improved the
performance of MySQL between 5.2 and 5.3.  The mixed news is that clearly
we have more work to do. :-)  Out of curiousity, has anyone done much in
the way of kernel profiling during heavy duty MySQL runs to see if there
are specific kernel bottlenecks we can be working on?

I've noticed that we're contending a fair amount on UNIX domain socket
locking, although with Giant off the stack this is a big improvement over
what we saw previously.  Although it was a few months ago, my recollection
from profiling the mutex use and kernel use is that we're spending a lot
of time checking to see if we have to deliver signals to threads or not in
kernel.  I may have the opportunity to do a bit of profiling today or
tomorrow and see what I bump into.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Principal Research Scientist, McAfee Research