Re: PostgreSQL and Ultrasparc T1

On Tue, 20 Dec 2005, Alan Stange wrote:

> David Lang wrote:
>> On Tue, 20 Dec 2005, Alan Stange wrote:
>>
>>> Jignesh K. Shah wrote:
>>>> I guess it depends on what you term as your metric for measurement.
>>>> If it is just one query execution time .. It may not be the best on
>>>> UltraSPARC T1.
>>>> But if you have more than 8 complex queries running simultaneously,
>>>> UltraSPARC T1 can do well compared comparatively provided the application
>>>> can scale also along with it.
>>>
>>> I just want to clarify one issue here. It's my understanding that the
>>> 8-core, 4 hardware thread (known as strands) system is seen as a 32 cpu
>>> system by Solaris. So, one could have up to 32 postgresql processes
>>> running in parallel on the current systems (assuming the application can
>>> scale).
>>
>> note that like hyperthreading, the strands aren't full processors, their
>> efficiancy depends on how much other threads shareing the core stall
>> waiting for external things.
> Exactly. Until we have a machine in hand (and substantial technical
> documentation) we won't know all the limitations.

by the way, when you do get your hands on it I would be interested to hear
how Linux compares to Solaris on the same hardware.

given how new the hardware is it's also likly that linux won't identify
the hardware properly (either seeing it as 32 true processors or just as 8
without being able to use the strands), so the intitial tests may not
reflect the Linux performance in a release or two.

David Lang