Re: How to analyze load average ?

On , Tomas Vondra wrote:
>> I think load avg is high because before I change the servers my
>> produce
>> server
>> was on 16 cpu, 24 gb memory and load avg on that server was 0.24.
>> Database is the same,
>> users that use the server is the same, nothing is changed. I dump
>> the DB
>> from old server
>> and import it to new one before few days ago and because that is the
>> new
>> server with more
>> resource I monitor his load avg and I think is too high. For that
>> reason
>> Im asking is there
>> a way to detect why my load avg is 0.88. When I run select * from
>> pg_stat_activity;
>> did not see more then 3-4 query that isn't much complicated and I
>> already try them with
>> explain to see what is the result.
>
> Well, the load average is a bit difficult to analyze because of the
> exponential damping. Also, I find it a bit artificial and if there
> are
> no sudden peaks or slowdowns I wouldn't bother analyzing this.
>
> A wild quess is that the new server has more CPUs but at lower
> frequency, therefore the tasks run longer and impact the load average
> accordingly. There are other such things (e.g. maintenance of larger
> shared buffers takes more time).
>
> Have you verified that the performance of the new hardware matches
> expectations and that it's actually faster than the old server?
>
>> I know what load average mean, I was OpenBSD user a few years, now I
>> use Slackware with kernel 3.5.
>
> So you do have 3.5 on production? Wow, you're quite adventurous.

Yep, that's me :)

>
> Tomas


Hello to every one again,
sorry for my late replay but I found the problem (I think).
I change the Default IO scheduler from (No-op) to Deadline and
my load average dropped down to 0.23