[HPGMG Forum] HPGMG release v0.1

Jeff Hammond jeff.science at gmail.com
Sat Jun 7 22:39:11 UTC 2014


On Sat, Jun 7, 2014 at 3:35 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
> On Jun 7, 2014, at 5:31 PM, Jeff Hammond <jeff.science at gmail.com> wrote:
>
>> On Sat, Jun 7, 2014 at 3:26 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>>
>>>   The use of multicore processor == sockets as the independent variable in the plot of aggregate performance seems arbitrary. Though people should not use this kind of plot to compare machines they will. Now just change sockets to nodes and boom suddenly the machines compare very differently (since some systems have two sockets per node and some one). Should cores be used instead? Or hardware threads? Or cores scaled by their clock speed? Or hardware floating point units (scaled by clock speed?) ? Or number of instruction decorders? Power usage? Cost? etc etc. Maybe have a dynamic plot where one can switch the independent variable by selecting from a menu or moving the mouse over choices ….?
>>
>    Yes, but how do we measure power? The actual amount being pulled from the “wall socket”? Is that possible? Like the various hardware features you mention I wouldn’t trust anything the vendor says about power.

Assuming you run on more than one node, just use the total machine
power that is used by Green500.  Granted, that is not ideal since it
won't be measured for the same code, but at least there is a
well-defined procedure for measuring it and hopefully it is at least
roughly comparable between systems.

But I agree that power is nearly as hard to get exactly right as
anything else besides counting nodes.  That is about the only
independent variable that seems unambiguous.

Jeff

>> The last suggestion is obviously the best one since it is the most
>> general, but I think power is the best choice of independent variable.
>> Most of the other hardware features are bad choices because it is very
>> hard to determine some of these.  What is the clock speed of an Intel
>> socket that does dynamic frequency scaling?  How do you count cores on
>> a GPU?  NVIDIA's core-counting methodology is complete nonsense...
>>
>> Best,
>>
>> Jeff
>>
>>
>>> On Jun 7, 2014, at 4:27 PM, Jed Brown <jed at jedbrown.org> wrote:
>>>
>>>> Mark Adams <mfadams at lbl.gov> writes:
>>>>> We are please to announce that hpgmg.org and the associated mailing
>>>>> list hpgmg-forum at hpgmg.org is officially available.
>>>>
>>>> Thanks, Mark.  To help kick off the discussion, I would like to call
>>>> attention to our recent blog posts describing "results".
>>>>
>>>> The most recent announces the v0.1 release and includes a Kiviat diagram
>>>> comparing the on-node performance characteristics of CORAL apps and
>>>> several benchmarks running on Blue Gene/Q.
>>>>
>>>> https://hpgmg.org/2014/06/06/hpgmg-01/
>>>>
>>>>
>>>> This earlier post shows performance on a variety of top machines:
>>>>
>>>> https://hpgmg.org/2014/05/15/fv-results/
>>>>
>>>>
>>>> We are interested in better ways to collect and present the comparison
>>>> data as well as any characteristics that you think are important.
>>>>
>>>>
>>>> In addition to the general principles on the front page, some further
>>>> rationale is given at:
>>>>
>>>> https://hpgmg.org/why/
>>>>
>>>> None of this is set in stone and we would be happy to discuss any
>>>> questions or comments on this list.
>>>>
>>>>
>>>> Please encourage any interested colleagues to subscribe to this list:
>>>>
>>>> https://hpgmg.org/lists/listinfo/hpgmg-forum
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>>>
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>>
>>
>>
>> --
>> Jeff Hammond
>> jeff.science at gmail.com
>> http://jeffhammond.github.io/
>



-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/


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