[libc-commits] [PATCH] D148288: [libc] Update RPC interface for system utilities on th GPU

[Joseph Huber via Phabricator via libc-commits]

jhuber6 created this revision.
jhuber6 added reviewers: JonChesterfield, jdoerfert, tianshilei1992, michaelrj, lntue, sivachandra, tra, gchatelet.
Herald added subscribers: libc-commits, kosarev, mattd, asavonic, ecnelises, kerbowa, tschuett, jvesely.
Herald added projects: libc-project, All.
jhuber6 requested review of this revision.

This patch reworks the RPC interface to allow more generic memory
operations using the shared better. This patch decomposes the entire RPC
interface into opening a port and calling `send` or `recv` on it.

The `send` function sends a single packet of the length of the buffer.
The `recv` function is paired with the `send` call to then use the data.
So, any aribtrary combination of sending packets is possible. The only
restriction is that the client initiates the exchange with a `send`
while the server consumes it with a `recv`.

The operation of this is driven by two independent state machines that
tracks the buffer ownership during loads / stores. We keep track of two
so that we can transition between a send state and a recv state without
an extra wait. State transitions are observed via bit toggling, e.g.

This interface supports an efficient `send -> ack -> send -> ack -> send`
interface and allows for the last send to be ignored without checking
the ack.

A following patch will add some more comprehensive testing to this interface. I
I informally made an RPC call that simply incremented an integer and it took
roughly 10 microsends to complete an RPC call.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D148288

Files:
  libc/src/__support/OSUtil/gpu/io.cpp
  libc/src/__support/OSUtil/gpu/io.h
  libc/src/__support/OSUtil/gpu/quick_exit.cpp
  libc/src/__support/RPC/rpc.h
  libc/startup/gpu/amdgpu/start.cpp
  libc/startup/gpu/nvptx/start.cpp
  libc/utils/gpu/loader/CMakeLists.txt
  libc/utils/gpu/loader/Server.h
  libc/utils/gpu/loader/amdgpu/CMakeLists.txt
  libc/utils/gpu/loader/amdgpu/Loader.cpp
  libc/utils/gpu/loader/nvptx/CMakeLists.txt
  libc/utils/gpu/loader/nvptx/Loader.cpp

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