Re: How can I make use of both CPUs in a dual processor

Thanks John.

Well as I mentioned. I have a Dual AMD Opteron 64 2.4ghz, 15k rpm SCSI
Disks, 4GB of memory.
Disks are pretty fast and memory should be more than enough. Currently
we dont have many concurrent connections.

I run PG 8.0.1 on Fedora Core 3

When I now run the batch job, one CPU runs in the 80-90% the other in
5-10% max.

John A Meinel wrote:

> Alex wrote:
>
>> Hi,
>> we just got a new dual processor machine and I wonder if there is a
>> way to utilize both processors.
>>
>> Our DB server is basically fully dedicated to postgres. (its a dual
>> amd with 4gb mem.)
>>
>> I have a batch job that periodically loads about 8 million records
>> into a table.
>> for this I drop the indices, truncate the table, use the copy to
>> insert the data, recreate the indices (4 indices), vacuum the table.
>>
>> That is all done through a perl batch job.
>>
>> While I am doing this, I noticed that only one CPU is really used.
>>
>> So here are my questions:
>>
>> Is there a way to utilize both CPUs
>>
> For postgres, you get a max of 1 CPU per connection, so to use both,
> you need 2 CPU's.
>
>> Is it possible to split up the import file and run 2 copy processes
>>
>> Is it possible to create 2 indices at the same time
>>
> You'd want to be a little careful. Postgres uses work_mem for vacuum
> and index creation, so if you have 2 processes doing it, just make
> sure you aren't running out of RAM and going to swap.
>
>> Would I actually gain anything from that, or is the bottleneck
>> somewhere else ?
>>
> More likely, the bottleneck would be disk I/O. Simply because it is
> almost always disk I/O. However, without knowing your configuration,
> how much CPU is used during the operation, etc, it's hard to say.
>
>> (perl is a given here for the batch job)
>>
>> If anyone has some experience or ideas... any hints or help on this
>> would be appreciated.
>>
>> Thanks
>> Alex
>>
> Sorry I wasn't a lot of help. You should probably post your postgres
> version, and more information about how much CPU load there is while
> your load is running.
>
> John
> =:->
>