Re: How to reduce IOWAIT and CPU idle time?

On Sat, Sep 10, 2016 at 8:49 PM, Samir Magar <samirmagar8(at)gmail(dot)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