Re: Renice on Postgresql process

[Peter J. Holzer]

On 2018-05-07 11:04:31 -0700, Ben Chobot wrote:
> On May 7, 2018, at 7:46 AM, Ayappan P2  wrote:
> We are using Postgresql in AIX. Unlike some other databases, Postgresql 
> has
> lot of other process running in the background along with the main 
> process.
> 
> We do "renice" only on the Postgres main process. Is it sufficient to have
> higher priority only for the main process or we have to do "renice" for 
> all
> the Postgresql related process ( like wal writer, logger , checkpointer
> etc.,) ?
> 
> 
> What do you hope to achieve with your renicing? There is a compelling school 
> of
> thought which holds that nice database processes take longer to relinquish
> their resources, which doesn't end up helping anything at all.

I think you misunderstood Ayappan. He doesn't want to make the database
processes nicer, he wants to make them less nice ("higher priority").

So in theory, they should be able to complete requests faster because
they aren't interrupted by other processes so often. 

Whether that is true, depends on whether the processes are cpu or disk
bound and what exactly the "nice value" affects. The best way to find
out is probably to try it.

hp

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|_|_) || because we have much more sophisticated
| |   | h...@hjp.at | management tools.
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Re: Renice on Postgresql process

[Joshua D. Drake]

On 05/23/2018 04:36 PM, Ben Chobot wrote:



On May 7, 2018, at 11:50 PM, Ayappan P2 > wrote:


We are doing "renice" on the main Postgresql process to give higher 
scheduling priority because other critical operations depends on the 
database.
You are saying that the database processes take longer to relinquish 
their resources and we won't achieve anything out of renice, So i 
assume renice of the database processes is not at all required ?

Thanks
Ayappan P


Yes, if you make a db process nicer than the db takes longer to answer 
your queries. If the goal is to keep the load down on the db, that is 
usually going to be counterproductive.


Correct or in other words, the problem is bad provisioning. You need to 
optimize your resources whether that be hardware/vm or code.


JD



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Re: Renice on Postgresql process

[Ben Chobot]

> On May 7, 2018, at 11:50 PM, Ayappan P2  wrote:
> 
> We are doing "renice" on the main Postgresql process to give higher 
> scheduling priority because other critical operations depends on the database.
> You are saying that the database processes take longer to relinquish their 
> resources and we won't achieve anything out of renice, So i assume renice of 
> the database processes is not at all required ?
>  
> Thanks
> Ayappan P
>  

Yes, if you make a db process nicer than the db takes longer to answer your 
queries. If the goal is to keep the load down on the db, that is usually going 
to be counterproductive.

Re: Renice on Postgresql process

[Ayappan P2]

We are doing "renice" on the main Postgresql process to give higher scheduling priority because other critical operations depends on the database.
You are saying that the database processes take longer to relinquish their resources and we won't achieve anything out of renice, So i assume renice of the database processes is not at all required ?
 
Thanks
Ayappan P
 
- Original message -From: Ben Chobot To: Ayappan P2 Cc: pgsql-general@lists.postgresql.orgSubject: Re: Renice on Postgresql processDate: Mon, May 7, 2018 11:35 PM On May 7, 2018, at 7:46 AM, Ayappan P2  wrote:

 
Hi All,We are using Postgresql in AIX. Unlike some other databases, Postgresql has lot of other process running in the background along with the main process. We do "renice" only on the Postgres main process. Is it sufficient to have higher priority only for the main process or we have to do "renice" for all the Postgresql related process ( like wal writer, logger , checkpointer etc.,) ?  

What do you hope to achieve with your renicing? There is a compelling school of thought which holds that nice database processes take longer to relinquish their resources, which doesn't end up helping anything at all.
 

Re: Renice on Postgresql process

[Ben Chobot]

On May 7, 2018, at 7:46 AM, Ayappan P2  wrote:
> 
> Hi All,
> 
> We are using Postgresql in AIX. Unlike some other databases, Postgresql has 
> lot of other process running in the background along with the main process. 
> 
> We do "renice" only on the Postgres main process. Is it sufficient to have 
> higher priority only for the main process or we have to do "renice" for all 
> the Postgresql related process ( like wal writer, logger , checkpointer 
> etc.,) ? 
> 

What do you hope to achieve with your renicing? There is a compelling school of 
thought which holds that nice database processes take longer to relinquish 
their resources, which doesn't end up helping anything at all.

Renice on Postgresql process

[Ayappan P2]

Hi All,

We are using Postgresql in AIX. Unlike some other databases, Postgresql has
lot of other process running in the background along with the main process.

We do "renice" only on the Postgres main process. Is it sufficient to have
higher priority only for the main process or we have to do "renice" for all
the Postgresql related process ( like wal writer, logger , checkpointer
etc.,) ?

Thanks
Ayappan P