Re: How to reduce IOWAIT and CPU idle time?

[Venkata B Nagothi <nag1010@xxxxxxxxx>]

On Sat, Sep 10, 2016 at 8:49 PM, Samir Magar <samirmagar8@xxxxxxxxx> 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