Re: Amazon EC2 CPU Utilization

[Jim Mlodgenski <jimmy76@xxxxxxxxx>]

On Wed, Jan 27, 2010 at 6:37 PM, Mike Bresnahan <mike.bresnahan@xxxxxxxxxxx> wrote:

Greg Smith <greg <at> 2ndquadrant.com> writes:
> Could you try this again with "top -c", which will label these
> postmaster processes usefully, and include the pgbench client itself in
> what you post?  It's hard to sort out what's going on in these
> situations without that style of breakdown.

As a further experiment, I ran 8 pgbench processes in parallel. The result is
about the same.

Let's start from the beginning. Have you tuned your postgresql.conf file? What do you have shared_buffers set to? That would have the biggest effect on a test like this. 

 

top - 18:34:15 up 17 min,  2 users,  load average: 0.39, 0.40, 0.36
Tasks: 217 total,   8 running, 209 sleeping,   0 stopped,   0 zombie
Cpu(s): 22.2%us,  8.9%sy,  0.0%ni, 68.7%id,  0.0%wa,  0.0%hi,  0.0%si,  0.3%st
Mem:   7358492k total,  1611148k used,  5747344k free,    11416k buffers
Swap:        0k total,        0k used,        0k free,  1248408k cached

 PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND

 1506 postgres  20   0  197m 134m 132m S 29.4  1.9   0:09.27 postgres: postgres
postgres [local] idle

 1524 postgres  20   0  197m 134m 132m R 29.4  1.9   0:05.13 postgres: postgres
postgres [local] idle

 1509 postgres  20   0  197m 134m 132m R 27.1  1.9   0:08.58 postgres: postgres
postgres [local] SELECT

 1521 postgres  20   0  197m 134m 132m R 26.4  1.9   0:05.77 postgres: postgres
postgres [local] SELECT

 1512 postgres  20   0  197m 134m 132m S 26.1  1.9   0:07.62 postgres: postgres
postgres [local] idle

 1520 postgres  20   0  197m 134m 132m R 25.8  1.9   0:05.31 postgres: postgres
postgres [local] idle

 1515 postgres  20   0  197m 134m 132m S 23.8  1.9   0:06.94 postgres: postgres
postgres [local] SELECT

 1527 postgres  20   0  197m 134m 132m S 21.8  1.9   0:04.46 postgres: postgres
postgres [local] SELECT

 1517 postgres  20   0 49808 2012 1544 R  5.3  0.0   0:01.02 pgbench -S -c 1 -T
30

 1507 postgres  20   0 49808 2012 1544 R  4.6  0.0   0:01.70 pgbench -S -c 1 -T
30

 1510 postgres  20   0 49808 2008 1544 S  4.3  0.0   0:01.32 pgbench -S -c 1 -T
30

 1525 postgres  20   0 49808 2012 1544 S  4.3  0.0   0:00.79 pgbench -S -c 1 -T
30

 1516 postgres  20   0 49808 2016 1544 S  4.0  0.0   0:01.00 pgbench -S -c 1 -T
30

 1504 postgres  20   0 49808 2012 1544 R  3.3  0.0   0:01.81 pgbench -S -c 1 -T
30

 1513 postgres  20   0 49808 2016 1544 S  3.0  0.0   0:01.07 pgbench -S -c 1 -T
30

 1522 postgres  20   0 49808 2012 1544 S  3.0  0.0   0:00.86 pgbench -S -c 1 -T
30

 1209 postgres  20   0 63148 1476  476 S  0.3  0.0   0:00.11 postgres: stats
collector process

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Jim Mlodgenski
EnterpriseDB (http://www.enterprisedb.com)