High system in %system load .

Ivan Voras ivoras at freebsd.org
Wed Nov 19 02:42:31 PST 2008


Igor Lyapin wrote:
> I already sent # top head in my first mail
> that's all non idle top process
> 
> last pid: 56920;  load averages:  2.90,  2.25,  1.72                 up
> 0+22:10:12  20:04:05
> 210 processes: 2 running, 207 sleeping, 1 zombie
> CPU states:  8.3% user,  0.0% nice, 32.5% system,  0.3% interrupt, 58.9%
> idle
> Mem: 1268M Active, 1904M Inact, 479M Wired, 154M Cache, 214M Buf, 125M Free
> Swap: 8192M Total, 8192M Free
> 
>   PID USERNAME       THR PRI NICE   SIZE    RES STATE  C   TIME   WCPU
> COMMAND
> 55546 www              1  -4    0   198M 24912K ufs    1   0:25 29.39% httpd
> 55986 www              1  -4    0   198M 23228K ufs    2   0:08 21.39% httpd
> 56030 www              1  -4    0   199M 23400K ufs    1   0:05 11.23% httpd

Ok, high sys load in "ufs" state for me was often caused by PHP session
storage. By default, PHP will store all session records in a single
directory, which can grow to monstruous sizes. If this is also your
case, here are some things to try:

a) increase vfs.ufs.dirhash_maxmem to 10 MB or something like that (look
at vfs.ufs.dirhash_mem to see if you're hitting the limit and if so,
monitor it to see what your dirhash_maxmem limit should be)
b) configure PHP to use "sharded" directory structure for sessions.

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