Re: Extremely high CPU usage when building tables - Mailing list pgsql-performance

From Rajesh Kumar Mallah
Subject Re: Extremely high CPU usage when building tables
Date
Msg-id AANLkTikyK6EtgIinzPIOwhokGJvR1Oq_fsHrUzA-k2we@mail.gmail.com
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In response to Extremely high CPU usage when building tables  (Deborah Fuentes <dfuentes@eldocomp.com>)
Responses Re: Extremely high CPU usage when building tables  (Deborah Fuentes <dfuentes@eldocomp.com>)
List pgsql-performance
Hi,

1. Did you also check vmstat output , from sar output the i/o wait is not clear.
2.  i gues you must be populating the database between creating tables and creating
     indexes. creating indexes require sorting of data that may be cpu intensive, loading/populating
     the data may saturate the i/o bandwidth . I think you should check when the max cpu utilisation
     is taking place exactly.

regds
Rajesh Kumar Mallah.

On Sat, Jun 26, 2010 at 3:55 AM, Deborah Fuentes <dfuentes@eldocomp.com> wrote:
Hello,

When I run an SQL to create new tables and indexes is when Postgres consumes all CPU and impacts other users on the server.

We are running Postgres 8.3.7 on a Sun M5000 with 2 x quad core CPUs (16 threads) running Solaris 10.

I've attached the sar data at the time of the run- here's a snip-it below.

Any ideas would be greatly appreciated.

Thanks!
Deb

****************************************************

Here, note the run queue, the left column. That is the number of processes waiting to run. 97 processes waiting to run at any time with only eight CPU cores looks very busy.

root@core2 # sar -q 5 500

SunOS core2 5.10 Generic_142900-11 sun4u    06/17/2010

12:01:50 runq-sz %runocc swpq-sz %swpocc
12:01:55     1.8      80     0.0       0
12:02:00     1.0      20     0.0       0
12:02:05     1.0      20     0.0       0
12:02:10     0.0       0     0.0       0
12:02:15     0.0       0     0.0       0
12:02:21     3.3      50     0.0       0
12:02:26     1.0      20     0.0       0
12:02:31     1.0      60     0.0       0
12:02:36     1.0      20     0.0       0
12:02:42    27.0      50     0.0       0
12:02:49    32.8      83     0.0       0
12:02:55    76.0     100     0.0       0
12:03:01    66.1     100     0.0       0
12:03:07    43.8     100     0.0       0
12:03:13    52.0     100     0.0       0
12:03:19    91.2     100     0.0       0
12:03:26    97.8      83     0.0       0
12:03:33    63.7     100     0.0       0
12:03:39    67.4     100     0.0       0
12:03:47    41.5     100     0.0       0
12:03:53    82.0      83     0.0       0
12:03:59    88.7     100     0.0       0
12:04:06    87.7      50     0.0       0
12:04:12    41.3     100     0.0       0
12:04:17    94.3      50     0.0       0
12:04:22     1.0      20     0.0       0
12:04:27     3.3      60     0.0       0
12:04:32     1.0      20     0.0       0
12:04:38     0.0       0     0.0       0


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