llvm-capstone/openmp/libomptarget
Shilei Tian a014fbbc21 [OpenMP] Improve D2D memcpy to use more efficient driver API
Summary:
In current implementation, D2D memcpy is first to copy data back to host and then
copy from host to device. This is very efficient if the device supports D2D
memcpy, like CUDA.

In this patch, D2D memcpy will first try to use native supported driver API. If
it fails, fall back to original way. It is worth noting that D2D memcpy in this
scenerio contains two ideas:
- Same devices: this is the D2D memcpy in the CUDA context.
- Different devices: this is the PeerToPeer memcpy in the CUDA context.
My implementation merges this two parts. It chooses the best API according to
the source device and destination device.

Reviewers: jdoerfert, AndreyChurbanov, grokos

Reviewed By: jdoerfert

Subscribers: yaxunl, guansong, sstefan1, openmp-commits

Tags: #openmp

Differential Revision: https://reviews.llvm.org/D80649
2020-06-04 16:59:06 -04:00
..
cmake/Modules [Openmp][VE] Libomptarget plugin for NEC SX-Aurora 2020-05-12 10:47:30 +02:00
deviceRTLs [OpenMP][NFC] Fix not sustitution in tests 2020-05-11 14:53:48 -04:00
include [OpenMP] Improve D2D memcpy to use more efficient driver API 2020-06-04 16:59:06 -04:00
plugins [OpenMP] Improve D2D memcpy to use more efficient driver API 2020-06-04 16:59:06 -04:00
src [OpenMP] Improve D2D memcpy to use more efficient driver API 2020-06-04 16:59:06 -04:00
test [OpenMP] Improve D2D memcpy to use more efficient driver API 2020-06-04 16:59:06 -04:00
CMakeLists.txt [OpenMP] build offload plugins before testing them 2019-11-28 17:43:56 -05:00
README.txt Unify build documentation and convert to reStructuredText 2017-12-27 09:15:10 +00:00

    README for the LLVM* OpenMP* Offloading Runtime Library (libomptarget)
    ======================================================================

How to Build the LLVM* OpenMP* Offloading Runtime Library (libomptarget)
========================================================================
In-tree build:

$ cd where-you-want-to-live
Check out openmp (libomptarget lives under ./libomptarget) into llvm/projects
$ cd where-you-want-to-build
$ mkdir build && cd build
$ cmake path/to/llvm -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler>
$ make omptarget

Out-of-tree build:

$ cd where-you-want-to-live
Check out openmp (libomptarget lives under ./libomptarget)
$ cd where-you-want-to-live/openmp/libomptarget
$ mkdir build && cd build
$ cmake path/to/openmp -DCMAKE_C_COMPILER=<C compiler> -DCMAKE_CXX_COMPILER=<C++ compiler>
$ make

For details about building, please look at README.rst in the parent directory.

Architectures Supported
=======================
The current library has been only tested in Linux operating system and the
following host architectures:
* Intel(R) 64 architecture
* IBM(R) Power architecture (big endian)
* IBM(R) Power architecture (little endian)
* ARM(R) AArch64 architecture (little endian)

The currently supported offloading device architectures are:
* Intel(R) 64 architecture (generic 64-bit plugin - mostly for testing purposes)
* IBM(R) Power architecture (big endian) (generic 64-bit plugin - mostly for testing purposes)
* IBM(R) Power architecture (little endian) (generic 64-bit plugin - mostly for testing purposes)
* ARM(R) AArch64 architecture (little endian) (generic 64-bit plugin - mostly for testing purposes)
* CUDA(R) enabled 64-bit NVIDIA(R) GPU architectures

Supported RTL Build Configurations
==================================
Supported Architectures: Intel(R) 64, IBM(R) Power 7 and Power 8

              ---------------------------
              |   gcc      |   clang    |
--------------|------------|------------|
| Linux* OS   |  Yes(1)    |  Yes(2)    |
-----------------------------------------

(1) gcc version 4.8.2 or later is supported.
(2) clang version 3.7 or later is supported.


Front-end Compilers that work with this RTL
===========================================

The following compilers are known to do compatible code generation for
this RTL:
  - clang (from https://github.com/clang-ykt )
  - clang (development branch at http://clang.llvm.org - several features still
    under development)

-----------------------------------------------------------------------

Notices
=======
This library and related compiler support is still under development, so the
employed interface is likely to change in the future.

*Other names and brands may be claimed as the property of others.