Webrev for first version of HSA offload integer reduce

[Christian Thalinger]

On Jun 9, 2014, at 10:50 AM, Eric Caspole <eric.caspole at amd.com> wrote:

> 
> 
> On 06/09/2014 01:07 PM, Christian Thalinger wrote:
>> 
>> On Jun 9, 2014, at 9:40 AM, Caspole, Eric <Eric.Caspole at amd.com
>> <mailto:Eric.Caspole at amd.com>> wrote:
>> 
>>> Hi everybody,
>>> I put up a new webrev that allows some IntStream.reduce() to be
>>> offloaded to HSA:
>>> 
>>> http://cr.openjdk.java.net/~ecaspole/graal_int_reduce1/webrev/
>> 
>> 
>>    src/gpu/hsail/vm/hsailKernelArguments.hpp
>> 
>> +  virtual void collectArgs() {
>> 
>> Does this really have to be in the .hpp file?  I see that the base class
>> has it in the .hpp file too.
> 
> No it doesn't have to be there, it is just some historical thing I don't know why. I can change that.

That would be good.  Thanks.

> 
>> 
>>> 
>>> This works with a Sumatra webrev I will eventually add into the
>>> Sumatra JDK repo:
>>> 
>>> http://cr.openjdk.java.net/~ecaspole/sumatra_int_reduce_1/webrev/
>>> 
>>> This combo allows offloading IntStream.parallel().reduce() for
>>> Integer::sum, Integer::max, and Integer::min. It builds a kernel from
>>> a hand made HSAIL string of code that gets called from the new Stream
>>> API diversion code in the Sumatra part.
>>> 
>>> Eventually we hope to have regular compilation of user reduce
>>> functions but this allows us to do experiments with workloads before
>>> we get all the details of reduce compilation in place such as barrier
>>> placement and group size nuances.
>> 
>> Presumably that will remove the hand-made code eventually?
> 
> Yes. I just want to be able to expose this interesting functionality in the mean time.

Makes sense.

> 
>> 
>>> 
>>> In the current Kaveri hardware version of Okra, it uses group size 256
>>> by default and this reduce code is designed to work only with 256.
>>> Also, because it is a handmade kernel, it only runs with
>>> -UseHSAILDeoptimization and -UseCompressedOops.
>>> In the included reduce tests, they will skip if the correct flags are
>>> not there for the tests to run correctly.
>>> 
>>> This webrev also changes the way the kernel args are processed to look
>>> at the actual args type rather than by the type signature of the
>>> kernel method.
>>> Regards,
>>> Eric