[Parallel_libs-commits] [PATCH] D24528: [SE] Pack global dev handle addresses

[Justin Lebar via Parallel_libs-commits]

jlebar added inline comments.

================
Comment at: streamexecutor/include/streamexecutor/DeviceMemory.h:170
@@ -166,3 +169,3 @@
   Device *TheDevice;  // Pointer to the device on which this memory lives.
   const void *Handle; // Platform-dependent value representing allocated memory.
   size_t ByteCount;   // Size in bytes of this allocation.
----------------
Clearly in the multithreaded case you can't modify a GlobalDeviceMemoryBase concurrently with a call to thenLaunch().  That's true of any parameters to any function call, so I am not sure that's even worth warning about.

What I was worried about was a single-threaded case, something like this:

  GlobalDeviceMemory<int> other_mem;
  {  
    GlobalDeviceMemory<int> mem;
    Stream->thenLaunch(foo_kernel, mem);
    other_mem = std::move(mem);
  }
  Stream->block();

Is this safe?  That is, do we use &mem.Handle only within thenLaunch?  (We don't actually have to have a separate scope and so on for us to hit this same problem.)

(I have to admit, if any of this is 5% of some applications' runtime, it seems like we could do a lot better even than what we have here.  I'm not sure how, but hot code is hot...)


https://reviews.llvm.org/D24528