[Beowulf] Theoretical vs. Actual Performance

[Prentice Bisbal]

Joe,

Thanks for the link. Based on that, they should be pretty close in 
performance, and mine are not, so I must be doing something wrong with 
my OpenBLAS build. Since ACML is dead, I was hoping I could use OpenBLAS 
moving forward.

Prentice

On 02/22/2018 06:01 PM, Joe Landman wrote:
> ACML is hand coded assembly.  Not likely that OpenBLAS will be much 
> better.  Could be similar.  c.f. 
> http://gcdart.blogspot.co.uk/2013/06/fast-matrix-multiply-and-ml.html
>
>
>
> On 02/22/2018 05:48 PM, Prentice Bisbal wrote:
>> Just rebuilt OpenBLAS 0.2.20 locally on the test system with GCC 
>> 6.1.0, and I'm only getting 91 GFLOPS. I'm pretty sure OpenBLAS 
>> performance should be close to ACML performance, if not better. I'll 
>> have to dig into this later. For now, I'm going to continue my 
>> testing using the ACML-based build and revisit the OpenBLAS 
>> performance later.
>>
>> Prentice
>>
>> On 02/22/2018 05:27 PM, Prentice Bisbal wrote:
>>> So I just rebuilt HPL using the ACML 6.1.0 libraries with GCC 6.1.0, 
>>> and I'm now getting 197 GFLOPS, so clearly there's a problem with my 
>>> OpenBLAS build. I'm going to try building OpenBLAS without the 
>>> dynamic arch support on the machine where I plan on running my 
>>> tests, and see if that version of the library is any better.
>>>
>>> Prentice
>>>
>>> On 02/22/2018 09:37 AM, Prentice Bisbal wrote:
>>>> Beowulfers,
>>>>
>>>> In your experience, how close does actual performance of your 
>>>> processors match up to their theoretical performance? I'm 
>>>> investigating a performances issue on some of my nodes. These are 
>>>> older systems using AMD Opteron 6274 processors. I found literature 
>>>> from AMD stating the theoretical performance of these processors is 
>>>> 282 GFLOPS, and my LINPACK performance isn't coming close to that 
>>>> (I get approximately ~33% of that).  The number I often hear 
>>>> mentioned is actual performance should be ~85%. of theoretical 
>>>> performance is that a realistic number your experience?
>>>>
>>>> I don't want this to be a discussion of what could be wrong at this 
>>>> point, we will get to that in future posts, I assure you!
>>>>
>>>
>>
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>