Re: Postmaster only takes 4-5% CPU - Mailing list pgsql-general

Thanks for your answers Jan, Arjen, Shridar and Scott:

Postmaster is back taking lots of CPU when needed. I guess you were
right about Postgres waiting for some I/O activity. Anyway, I was not
able to see what process was responsible for this, since top showed
nothing remarkable.

This is a new top while running a VACUUM of the database:

   8:51pm  up  6:30,  3 users,  load average: 0,45, 0,11, 0,04
93 processes: 89 sleeping, 4 running, 0 zombie, 0 stopped
CPU states:  0,1% user,  1,1% system,  0,0% nice, 98,6% idle
Mem:  1031012K av, 1019612K used,   11400K free,  0K shrd,   44896K buff
Swap: 2040244K av,    1716K used, 2038528K free          894008K cached

   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
  1673 postgres  15   0  5120 5120  3196 R     0,9  0,4   0:02 postmaster
  1683 root      15   0  1044 1044   840 R     0,1  0,1   0:00 top
     1 root      15   0   476  476   424 S     0,0  0,0   0:04 init
     2 root      15   0     0    0     0 SW    0,0  0,0   0:00 keventd
     3 root      15   0     0    0     0 SW    0,0  0,0   0:00 kapmd
     4 root      34  19     0    0     0 SWN   0,0  0,0   0:00
ksoftirqd_CPU0
     5 root      15   0     0    0     0 SW    0,0  0,0   0:00 kswapd
     6 root      15   0     0    0     0 SW    0,0  0,0   0:00 bdflush
     7 root      15   0     0    0     0 SW    0,0  0,0   0:00 kupdated
     8 root      25   0     0    0     0 SW    0,0  0,0   0:00 mdrecoveryd
    12 root      15   0     0    0     0 SW    0,0  0,0   0:00 kjournald
    66 root      15   0     0    0     0 SW    0,0  0,0   0:00 khubd
   266 root      15   0     0    0     0 SW    0,0  0,0   0:00 kjournald
   267 root      15   0     0    0     0 SW    0,0  0,0   0:00 kjournald
   268 root      15   0     0    0     0 SW    0,0  0,0   0:05 kjournald
   269 root      15   0     0    0     0 SW    0,0  0,0   0:00 kjournald
   547 root      15   0     0    0     0 SW    0,0  0,0   0:00 eth0

Cheers, Ruben.


Jan Poslusny wrote:
> Did not your postmaster wait for harddisk ?
>
> Ruben wrote:
>
>> Hi all:
>>
>> When I run a (big) query from pgsql, postmaster used to take almost
>> 100% of CPU. Now, with aparent no reason, Postmaster only takes 4-5%
>> CPU and the same query takes really longer to finish.
>>
>> I have tried renicing -20 postmaster but it still only takes a small
>> percentage of CPU, while 90% is idle.
>>
>> This is a "top" screen while running the query:
>>
>>   2:27pm  up 5 min,  2 users,  load average: 0,80, 0,26, 0,08
>> 74 processes: 72 sleeping, 2 running, 0 zombie, 0 stopped
>> CPU states:  3,1% user,  2,1% system,  0,0% nice, 94,6% idle
>> Mem:  1031012K av,  246040K used,  784972K free,       0K shrd,
>> 11496K buff
>> Swap: 2040244K av,       0K used, 2040244K free
>> 196916K cached
>>
>>   PID USER     PRI  NI  SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
>>  1165 postgres   0 -20  3476 3476  2912 D <   4,5  0,3   0:02 postmaster
>>   268 root      15   0     0    0     0 SW    0,1  0,0   0:00 kjournald
>>
>> Any idea of how can I get postmaster to eat as much CPU as possible?
>>
>> Thanks a lot! Ruben.
>>
>>
>> ---------------------------(end of broadcast)---------------------------
>> TIP 4: Don't 'kill -9' the postmaster