Re: High load average in 64-core server , no I/O wait and CPU is idle

On 05/24/2012 12:26 AM, Rajesh Kumar. Mallah wrote:
>
> ----- "Claudio Freire"<klaussfreire@gmail.com>  wrote:
>
> | From: "Claudio Freire"<klaussfreire@gmail.com>
> | To: "Rajesh Kumar. Mallah"<mallah@tradeindia.com>
> | Cc: pgsql-performance@postgresql.org
> | Sent: Thursday, May 24, 2012 9:23:43 AM
> | Subject: Re: [PERFORM] High load average in 64-core server , no I/O wait and CPU is idle
> |
> | On Thu, May 24, 2012 at 12:39 AM, Rajesh Kumar. Mallah
> |<mallah@tradeindia.com>  wrote:
> |>  The problem is that  sometimes there are spikes of load avg which
> |>  jumps to>  50 very rapidly ( ie from 0.5 to 50  within 10 secs) and
> |>  it remains there for sometime and slowly reduces to normal value.
> |>
> |>  During such times of high load average we observe that there is no
> | IO wait
> |>  in system and even CPU is 50% idle. In any case the IO Wait always
> | remains<  1.0 % and
> |>  is mostly 0. Hence the load is not due to high I/O wait which was
> | generally
> |>  the case with our previous hardware.
> |
> | Do you experience decreased query performance?
>
>
> Yes we do experience substantial application performance degradations.
>
>

Maybe you are hitting some locks?   If its not IO and not CPU then maybe something is getting locked and queries are
pilingup. 

-Andy