6.8 became very slow

Bill Moran wmoran at potentialtech.com
Thu Jan 29 05:26:57 PST 2009


In response to Artem Kuchin <matrix at itlegion.ru>:

> I have  a very strange situation here. There was a hosting box with 5 
> jails.
> Everything is 6.4
> It was running twe driver with RAID 5.
> 
> Then i had a crash and had to reinstall the system.
> 
> So, i have installed FREEBSD 6.8, cvsed the latest, rebuilt everything 
> and then
> just copied jails from the prev installation. So, the host system is 6.8 
> and the jails are 6.4.
> Also, raid is MIRROR now, not RAID5.

OK.  I originally thought your subject was a typo, but this is the
second place where you mentioned 6.8.

Not only would you have to go into the future to get 6.8, but you'd
have to slip into an alternate reality, since 6.5 is expected to be
the last release on the 6 branch.

What is the output of uname -a?  If you really have something called
6.8, where on earth did you get it?

> The problem is that now everything became really slow.
> 
> When i do top i see:
> load averages: 16.45, 14.86, 13.86
> 737 processes: 20 running, 703 sleeping, 14 zombie
> CPU: 15.9% user,  0.0% nice, 81.9% system,  2.2% interrupt,  0.0% idle
> 
> Everything pretty much as it was. But 82% system CPU is really weird. I 
> don;t remember
> exactly, but i think it was not like this before. AFAIK it meas 82% of 
> CPU time is spent in
> the kernel.

gstat output seems to indicate nothing unusual, so the time spent in
the kernel must be for something else, network traffic maybe?  Try
checking top with -m io to see if anything is showing an unusually
high # of context switches.

Perhaps do a little easter egg hunting and try shutting down processes
to see what is using up all the system time.  Once you've got it
narrowed down you can run ktrace on the problematic process to see
what it's doing.

HTH

-- 
Bill Moran
http://www.potentialtech.com
http://people.collaborativefusion.com/~wmoran/


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