Re: [RFC PATCH 00/14] Heterogeneous Memory System (HMS) and hbind()

["Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>]

On 12/5/18 12:19 AM, Jerome Glisse wrote:

> Above example is for migrate. Here is an example for how the
> topology is use today:
> 
>      Application knows that the platform is running on have 16
>      GPU split into 2 group of 8 GPUs each. GPU in each group can
>      access each other memory with dedicated mesh links between
>      each others. Full speed no traffic bottleneck.
> 
>      Application splits its GPU computation in 2 so that each
>      partition runs on a group of interconnected GPU allowing
>      them to share the dataset.
> 
> With HMS:
>      Application can query the kernel to discover the topology of
>      system it is running on and use it to partition and balance
>      its workload accordingly. Same application should now be able
>      to run on new platform without having to adapt it to it.
> 

Will the kernel be ever involved in decision making here? Like the 
scheduler will we ever want to control how there computation units get 
scheduled onto GPU groups or GPU?

> This is kind of naive i expect topology to be hard to use but maybe
> it is just me being pesimistics. In any case today we have a chicken
> and egg problem. We do not have a standard way to expose topology so
> program that can leverage topology are only done for HPC where the
> platform is standard for few years. If we had a standard way to expose
> the topology then maybe we would see more program using it. At very
> least we could convert existing user.
> 
> 

I am wondering whether we should consider HMAT as a subset of the ideas
mentioned in this thread and see whether we can first achieve HMAT 
representation with your patch series?

-aneesh