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Re: How to reduce IOWAIT and CPU idle time? - Mailing list pgsql-performance

From Venkata B Nagothi
Subject Re: How to reduce IOWAIT and CPU idle time?
Date
Msg-id CAEyp7J8ADsd0AB7+f7-BQcC5hjOdycgqCCvRk7NHxNyOCh8cXQ@mail.gmail.com
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In response to How to reduce IOWAIT and CPU idle time?  (Samir Magar <samirmagar8@gmail.com>)
Responses Re: How to reduce IOWAIT and CPU idle time?  (Samir Magar <samirmagar8@gmail.com>)
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On Sat, Sep 10, 2016 at 8:49 PM, Samir Magar <samirmagar8@gmail.com> wrote:
Hello,


My Application has normally 25 to 30 connections and it is doing lot of insert/update/delete operation.
The database size is 100GB. 
iowait  is at 40% to 45 % and CPU idle time is at 45% to 50%
TOTAL RAM = 8 GB   TOTAL CPU = 4 

postgresql.conf parametre:

shared_buffers = 2GB
work_mem = 100MB
effective_cache_size = 2GB
maintenance_work_mem = 500MB
autovacuum = off
wal_buffers = 64MB


How can i reduce iowait and CPU idle time. It is slowing all the queries. The queries that used to take 1 sec,it is taking 12-15 seconds.

That does not point out the specific problem you are facing. Queries can slow down for a lot of reasons like as follows -

- Lack of maintenance
- Bloats in Tables and Indexes
- Data size growth
- If writes are slowing down, then it could be because of slow disks

Are you saying that queries are slowing down when there are heavy writes ? Are you referring to SELECTs or all types of queries ?

Regards,
Venkata B N

Fujitsu Australia 

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