Possible Threading problem with -CURRENT / MySQL?

Julian Elischer julian at elischer.org
Tue Jun 15 23:21:08 GMT 2004

On Mon, 14 Jun 2004, mike wrote:

> welcome to our hell. we've been experiencing mysql problems on freebsd 5.x
> as well. it sounds like scheduler/threading is to blame but we were not
> able to give sufficient or proper motivation to the folks who could
> examine this deeper - we even offered $500 cash to whomever stepped up to
> help resolve this.
> linux runs almost 2x as fast on the same hardware with no configuring -
> and we get nearly the same results running in single CPU mode vs. dual CPU
> mode on fbsd... something is definately fubar with the mysql+fbsd5.x
> combination.
You complained about this some time ago and you have still not responded 
with the information I suggest..

---- quote from my previous mail---------------
I'm not saying I can help particularly
but the problem is that the people who can help are generally not
interested in databases.. what needs to happen is for 
some analysis to be made as to where the time is being spent..
I vaguely remember you saying htat teh cpu was not piegged when you had
this problem... You didn't indicate whether the disks were at 100%.

to check this you should try running systat -vmstat
while noticing the slowdown and try see what is at 100%.
if it turns out that you are NOT seeing disk or CPU limitted
then the next step would be to take a snapshot of operations using 
ktrace -d -p (pid)  for 20 second followe by krtace -C to turn it off

then looking at the output may give an idea of what operations are
taking too long, and what is waiting on what..



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