Summary:
After experimenting with CUDA, I realized that we really only need to
set the active context right before creating an object such as a stream
or a device memory allocation. When we go on to use these objects later,
it is fine if the context that created them is no longer active,
operations with those objects will succeed anyway.
Since it turns out that we don't have to check the active context for
every operation, it makes sense to hide this active context from users
(by removing the "ActiveDeviceForThread" setter and getter) and to
change the Acxxel API to explicitly pass in the device ID to create
objects.
This change improves the Acxxel API and greatly simplifies the CUDA and
OpenCL implementations because they no longer require thread_local data.
Reviewers: jlebar, jprice
Subscribers: mgorny, parallel_libs-commits
Differential Revision: https://reviews.llvm.org/D26050
llvm-svn: 285372
Summary:
Acxxel is basically a simplified redesign of StreamExecutor.
Here are the major points where Acxxel differs from the current
StreamExecutor design:
* Acxxel doesn't support the kernel and kernel loader types designed for
emission by the compiler to support type-safe kernel launches. For
CUDA, kernels in Acxxel can be seamlessly launched using the standard
CUDA triple-chevron kernel launch syntax that is available with clang
and nvcc. For CUDA and OpenCL, kernel arguments can be passed in the
old-fashioned way, as one array of pointers to arguments and another
array of argument sizes. Although OpenCL doesn't get a type-safe
kernel launch method, it does still get the benefit of all the memory
management wrappers. In the future, clang may add support for
triple-chevron OpenCL kernel launchs, or some other type-safe OpenCL
kernel launch method.
* Acxxel does not depend on any other code in LLVM, so it builds
completely independently from LLVM.
The goal will be to check in Acxxel and remove StreamExecutor, or
perhaps to remove the old StreamExecutor and rename Acxxel to
StreamExecutor, so I think Acxxel should be thought of as a new version
of StreamExecutor, not as a separate project.
Reviewers: jlebar, jprice
Subscribers: beanz, mgorny, modocache, parallel_libs-commits
Differential Revision: https://reviews.llvm.org/D25701
llvm-svn: 285111
Jason Henline