Dual-CPU slower then Single under HP? 
Author Message
 Dual-CPU slower then Single under HP?

Morning all ...

        Have a client that is running an HP server, specs as follows:

Quote:
> HP-UX 11.00 HP 9000 L-200, Dual CPU (400MHz - 64 bit),
> OS Disk: 9GB U2W-LVD SCSI, 10K rpm

        They are trying to determine whether or not it will be able to
handle their environment, and we're trying to help them from the PgSQL
side of things ...

        They've got one of the HP developers working side-by-side with
them, looking at the hardware itself, and they've found:

" Running two concurrent Psql/Postgres processes made things worse. They
are blocking each other on semaphores. Elapsed time went from 4m:30s to
6m:15s (100K inserts)."

        The 4m:30s is running one process for 100K inserts ... with two
CPUs/processes, it increases the time to process by almost 40% ... ?

        Does this make sense?

        Looking at disk IO during the inserts, its pretty much dead ...
other then the occasional 'burst' to disk, the disks are quiet, so its all
getting tied up in CPU ...

        Thoughts?  Suggestions?  Other things to investigate that I'm not
thinking of?

Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy


---------------------------(end of broadcast)---------------------------



Mon, 24 Nov 2003 01:37:01 GMT
 Dual-CPU slower then Single under HP?


Quote:
>    The 4m:30s is running one process for 100K inserts ... with two
> CPUs/processes, it increases the time to process by almost 40% ... ?

Do you mean two processes inserting into the same table?

I committed some changes recently that reduce the amount of contention
involved in that scenario, but it's not released yet.

Another fairly likely issue is the not-very-good implementation of
spinlocks.  We've talked about finding a way other than select() to
block on a spinlock, but no one's done anything about it yet...

                        regards, tom lane

---------------------------(end of broadcast)---------------------------



Mon, 24 Nov 2003 02:28:04 GMT
 Dual-CPU slower then Single under HP?

Quote:


> >       The 4m:30s is running one process for 100K inserts ... with two
> > CPUs/processes, it increases the time to process by almost 40% ... ?

> Do you mean two processes inserting into the same table?

Yup ...

Quote:
> I committed some changes recently that reduce the amount of contention
> involved in that scenario, but it's not released yet.

So, this is one of those "known problem, improved in v7.2" sort of issues?

---------------------------(end of broadcast)---------------------------
TIP 3: if posting/reading through Usenet, please send an appropriate

message can get through to the mailing list cleanly



Mon, 24 Nov 2003 03:12:23 GMT
 Dual-CPU slower then Single under HP?

Great, thanks :)

Quote:


> > So, this is one of those "known problem, improved in v7.2" sort of issues?

> Yup.

>                    regards, tom lane

Marc G. Fournier                   ICQ#7615664               IRC Nick: Scrappy


---------------------------(end of broadcast)---------------------------
TIP 2: you can get off all lists at once with the unregister command



Mon, 24 Nov 2003 03:32:56 GMT
 Dual-CPU slower then Single under HP?

Quote:
> So, this is one of those "known problem, improved in v7.2" sort of issues?

Yup.

                        regards, tom lane

---------------------------(end of broadcast)---------------------------
TIP 2: you can get off all lists at once with the unregister command



Mon, 24 Nov 2003 03:47:13 GMT
 
 [ 5 post ] 

 Relevant Pages 

1. Dual AMD runs slower than single intel CPU

2. Unexpected Hi-Lo CPU Usage After Upgrade From Single To Dual CPU

3. Dual CPU box has worse SQL Server performance than single

4. Process Hogs Dual HP-UX CPUs: Why

5. CPU Spin on dual Xeon CPU's.

6. Dual CPU or Faster CPU better?

7. Dual-CPU RAID database server: What Hardware ?

8. Ingres II/2.0 9808 on NT w/dual CPU

9. CPU utilization on dual box?

10. SQL 2000 performance on dual CPU

11. Dual CPU Configuration

12. Best Config for DUAL CPU Informix Server?


 
Powered by phpBB® Forum Software