Generalize GPU indexing to add global indexing #1334
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MrBurmark
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artv3,
rhornung67,
CRobeck,
ajkunen,
mdavis36 and
rchen20
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I wanted to put this out here for feedback before I went too far. I'm curious what people think of the design and if anyone (@ajkunen) thought the slight differences between things like thread and block implementations were significant. I plan to do a before and after with the perf suite at some point to ensure performance but it passes the tests. |
@MrBurmark do you mean that the perf suite test passes? There are compilation issues related to global index types in CUDA builds here. |
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I haven't tried to change cuda yet in this branch so that's why its failing. I have not yet run this in the PerfSuite to look at performance, I wanted to be sure if anyone had ideas about the design that I incorporated them before I worried about that too much. |
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@MrBurmark gotcha. I will take a closer look today and provide feedback. Is there anything in particular that you think needs deeper scrutinizing? |
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I'll add comments on some of the things that I think are worth noting/thinking about. |
test/functional/kernel/nested-loop/test-kernel-nested-loop.cpp.in
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Should we get this in for the patch release? |
No. This is bigger than a bugfix. |
test/functional/kernel/nested-loop/test-kernel-nested-loop.cpp.in
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Add Hip Indexing classes so we can make more generic kernel For/Tile statements and launch loop implementations.
…ernelGpuGlobalIndexing
…ernelGpuGlobalIndexing
Yes coming soon to a PR near you. |
in MemUtils occupancy calculator methods
Generalize GPU indexing to add GPU global indexing
Add a global (thread and block) indexing class that abstracts indexing in a certain dimension. With this you can specify a block size or a grid size at compile time or get those values at runtime. You can also ignore blocks and index only with threads and vice versa.
The kernel and launch policies are now shared. The policy is multi-part and contains a global indexing class, a way to map those global indices like direct or strided loop, and a synchronization requirement. The synchronizatoin requirement allows you to request that all threads make it through the even if some have no work so you can synchronize the block.
I added aliases for all of the pre-existing policies and deprecated some in favor more consistently named policies.
One breaking change is that thread loop policies are no longer safe to block synchronize under, that feature still exists but can only be accessed with a custom policy.
This reduces duplication in the implementations of For and Tile statements in kernel and launch. This cuts down the number of implementations to just one for the direct polices and two for the loop policies as loop policies can differ base on whether you can synchronize inside them. I'm still working on thinking about some slight changes that came in now that things are more uniform.