Discussion:
High %SYS CPU usage
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Cesar Martin
2012-10-30 12:54:23 UTC
Permalink
Hello there,

I have PostgreSQL 8.3.18 server running on Centos 6.2 (2.6.32-220.7.1) with
this specs:

2x CPU AMD Opteron 6282
128GB RAM
Raid 10 (12HD 15k rpm 1GB cache) with data
Raid 10 (4HD 15k rpm 1GB cache) with xlog
Raid 1 (15k rpm 1GB cache shared with xlog) with system

On this server I have only one database with 312GB of data. The database
had run fine during 4 months, but from two months ago, during high work
load periods, the server is collapsed by "%sys" type load.

For example "dstat -ar --socket --tcp" during %sys load problem:
http://pastebin.com/7zfDNvPh

Reboot the server mitigates the problem during few days, but always
reappear.
Server not is swapping, don't have excessive I/O, don't have %IRQ load.

I don't have any ideas...

Thank you very much for your help.

My sysctl and postgres.conf:

sysclt -a:
http://pastebin.com/EEVnNxsZ

My Postgres.conf:
max_connections = 500 # (change requires restart)
unix_socket_directory = '/var/run/postgres' # (change requires restart)
shared_buffers = 18GB # min 128kB or max_connections*16kB
work_mem = 30MB # min 64kB
maintenance_work_mem = 1GB # min 1MB
max_fsm_pages = 8553600 # min max_fsm_relations*16, 6 bytes each
max_fsm_relations = 409000 # min 100, ~70 bytes each
fsync = on # turns forced synchronization on or off
synchronous_commit = off # immediate fsync at commit
wal_buffers = 8MB # min 32kB
checkpoint_segments = 64 # in logfile segments, min 1, 16MB each
checkpoint_completion_target = 0.9 # checkpoint target duration, 0.0 - 1.0
archive_mode = on # allows archiving to be done
archive_command = 'exit 0'
effective_cache_size = 100GB
constraint_exclusion = on
default_text_search_config = 'pg_catalog.spanish'
max_locks_per_transaction = 100
--
César Martín Pérez
***@gmail.com
Josh Berkus
2012-10-30 19:07:37 UTC
Permalink
Cesar,
Post by Cesar Martin
On this server I have only one database with 312GB of data. The database
had run fine during 4 months, but from two months ago, during high work
load periods, the server is collapsed by "%sys" type load.
Hmmm. Have you updated Linux any time recently? I'm wondering if this
is a PostgreSQL problem at all. It sounds like an OS issue.

Can you give us the results of mpstat -P ALL 3 ? The dstat output
doesn't tell me much.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
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Cesar Martin
2012-11-02 07:47:42 UTC
Permalink
Hi Josh,

Today is not the worse day for this issue, because Fridays DB have little
workload... But I have this output:

http://pastebin.com/bKg8tfKC

I don't have updated OS server from the install.
I also begin to think that the problem is OS misconfiguration (Kernel
parameters??) or Hardware problem...

Thanks for your help.
Post by Josh Berkus
Cesar,
Post by Cesar Martin
On this server I have only one database with 312GB of data. The database
had run fine during 4 months, but from two months ago, during high work
load periods, the server is collapsed by "%sys" type load.
Hmmm. Have you updated Linux any time recently? I'm wondering if this
is a PostgreSQL problem at all. It sounds like an OS issue.
Can you give us the results of mpstat -P ALL 3 ? The dstat output
doesn't tell me much.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
--
http://www.postgresql.org/mailpref/pgsql-performance
--
César Martín Pérez
***@gmail.com
Cesar Martin
2012-12-31 13:08:10 UTC
Permalink
Finally I resolv the problem
setting /sys/kernel/mm/redhat_transparent_hugepage/enabled to "never"
Post by Cesar Martin
Hi Josh,
Today is not the worse day for this issue, because Fridays DB have little
http://pastebin.com/bKg8tfKC
I don't have updated OS server from the install.
I also begin to think that the problem is OS misconfiguration (Kernel
parameters??) or Hardware problem...
Thanks for your help.
Post by Josh Berkus
Cesar,
Post by Cesar Martin
On this server I have only one database with 312GB of data. The database
had run fine during 4 months, but from two months ago, during high work
load periods, the server is collapsed by "%sys" type load.
Hmmm. Have you updated Linux any time recently? I'm wondering if this
is a PostgreSQL problem at all. It sounds like an OS issue.
Can you give us the results of mpstat -P ALL 3 ? The dstat output
doesn't tell me much.
--
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com
--
)
http://www.postgresql.org/mailpref/pgsql-performance
--
César Martín Pérez
--
César Martín Pérez
***@gmail.com
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