Hi,

can sombody tell me if I can benefit from PDQ on single processor system ?

According Informix performance guide, multiple treads are started when
when PDQ is used, but can i benefit from this wif one physical processor
is available only ? I am afraid the extra work to manage the multiple
threads will be bad for the overall Informix performance on a single
processor system ?

Is it better to set PDQ_MAXPRIORITY to 0 in case a single processor
system is used ?

Any experience ?

Regards ...

Joerg

Possibly it depends upon your hardware. Multi-cored and multi-threaded
processors possibly would benefit from multiple cpu vps, but wih an elderly,
single-core, single processor your concern that you may lose more on the
swings of conext switching than you gain on the roundabouts of Informix
parallel processing may well be founded.

--
Neil Truby t:01932 724027
Director m:07798 811708
Ardenta Limited e:neil.truby@ardenta.com

"Jörg RÃ1/4schenschmidt" <jrueschenschmidt@t-online.de> wrote in message
news:ehv3q4$1qp$00$1@news.t-online.com...
> Hi,
>
> can sombody tell me if I can benefit from PDQ on single processor system ?
>
> According Informix performance guide, multiple treads are started when
> when PDQ is used, but can i benefit from this wif one physical processor
> is available only ? I am afraid the extra work to manage the multiple
> threads will be bad for the overall Informix performance on a single
> processor system ?
>
> Is it better to set PDQ_MAXPRIORITY to 0 in case a single processor system
> is used ?
>
> Any experience ?
>
> Regards ...
>
> Joerg

I think if you have multiple disks then more then the disks can be
accessed in parallel rather than serially. Its then a balance point of
how busy the ready Q becomes to process the data returned from the
disks 2 disks may be OK, 10 may swamp the the ready Q


Jörg RÃ1/4schenschmidt wrote:
> Hi,
>
> can sombody tell me if I can benefit from PDQ on single processor system ?
>
> According Informix performance guide, multiple treads are started when
> when PDQ is used, but can i benefit from this wif one physical processor
> is available only ? I am afraid the extra work to manage the multiple
> threads will be bad for the overall Informix performance on a single
> processor system ?
>
> Is it better to set PDQ_MAXPRIORITY to 0 in case a single processor
> system is used ?
>
> Any experience ?
>
> Regards ...
>
> Joerg

Don't underestimate the memory restrictions when not using PDQ_PRIORITY.

Still when using version 10.00 or later 9.40s, DS_NONPDQ_QUERY_MEM can also help out here.

Regards,
Andreas