device_selector.cpp

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//==------ device_selector.cpp - SYCL device selector ----------------------==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
 
#include <CL/sycl/backend_types.hpp>
#include <CL/sycl/detail/device_filter.hpp>
#include <CL/sycl/device.hpp>
#include <CL/sycl/device_selector.hpp>
#include <CL/sycl/exception.hpp>
#include <CL/sycl/stl.hpp>
#include <detail/config.hpp>
#include <detail/device_impl.hpp>
#include <detail/filter_selector_impl.hpp>
#include <detail/force_device.hpp>
#include <detail/global_handler.hpp>
#include <sycl/ext/oneapi/filter_selector.hpp>
// 4.6.1 Device selection class
 
#include <algorithm>
#include <cctype>
#include <regex>
 
__SYCL_INLINE_NAMESPACE(cl) {
namespace sycl {
 
// Utility function to check if device is of the preferred backend.
// Currently preference is given to the level_zero backend.
static bool isDeviceOfPreferredSyclBe(const device &Device) {
  if (Device.is_host())
    return false;
 
  return detail::getSyclObjImpl(Device)->getPlugin().getBackend() ==
         backend::ext_oneapi_level_zero;
}
 
device device_selector::select_device() const {
  std::vector<device> devices = device::get_devices();
  int score = REJECT_DEVICE_SCORE;
  const device *res = nullptr;
 
  for (const auto &dev : devices) {
    int dev_score = (*this)(dev);
 
    if (detail::pi::trace(detail::pi::TraceLevel::PI_TRACE_ALL)) {
      std::string PlatformName = dev.get_info<info::device::platform>()
                                     .get_info<info::platform::name>();
      std::string DeviceName = dev.get_info<info::device::name>();
      std::cout << "SYCL_PI_TRACE[all]: "
                << "select_device(): -> score = " << dev_score
                << ((dev_score < 0) ? " (REJECTED)" : "") << std::endl
                << "SYCL_PI_TRACE[all]: "
                << "  platform: " << PlatformName << std::endl
                << "SYCL_PI_TRACE[all]: "
                << "  device: " << DeviceName << std::endl;
    }
 
    // A negative score means that a device must not be selected.
    if (dev_score < 0)
      continue;
 
    // SYCL spec says: "If more than one device receives the high score then
    // one of those tied devices will be returned, but which of the devices
    // from the tied set is to be returned is not defined". Here we give a
    // preference to the device of the preferred BE.
    //
    if ((score < dev_score) ||
        (score == dev_score && isDeviceOfPreferredSyclBe(dev))) {
      res = &dev;
      score = dev_score;
    }
  }
 
  if (res != nullptr) {
    if (detail::pi::trace(detail::pi::TraceLevel::PI_TRACE_BASIC)) {
      std::string PlatformName = res->get_info<info::device::platform>()
                                     .get_info<info::platform::name>();
      std::string DeviceName = res->get_info<info::device::name>();
      std::cout << "SYCL_PI_TRACE[all]: "
                << "Selected device ->" << std::endl
                << "SYCL_PI_TRACE[all]: "
                << "  platform: " << PlatformName << std::endl
                << "SYCL_PI_TRACE[all]: "
                << "  device: " << DeviceName << std::endl;
    }
    return *res;
  }
 
  throw cl::sycl::runtime_error("No device of requested type available.",
                                PI_DEVICE_NOT_FOUND);
}
 
int default_selector::operator()(const device &dev) const {
 
  int Score = REJECT_DEVICE_SCORE;
 
  // Give preference to device of SYCL BE.
  if (isDeviceOfPreferredSyclBe(dev))
    Score = 50;
 
  // If SYCL_DEVICE_FILTER is set, filter device gets a high point.
  // All unmatched devices should never be selected.
  detail::device_filter_list *FilterList =
      detail::SYCLConfig<detail::SYCL_DEVICE_FILTER>::get();
  // device::get_devices returns filtered list of devices.
  // Keep 1000 for default score when filters were applied.
  if (FilterList)
    Score = 1000;
 
  if (dev.get_info<info::device::device_type>() == detail::get_forced_type())
    Score += 1000;
 
  if (dev.is_gpu())
    Score += 500;
 
  if (dev.is_cpu())
    Score += 300;
 
  if (dev.is_host())
    Score += 100;
 
  // Since we deprecate SYCL_BE and SYCL_DEVICE_TYPE,
  // we should not disallow accelerator to be chosen.
  // But this device type gets the lowest heuristic point.
  if (dev.is_accelerator())
    Score += 75;
 
  return Score;
}
 
int gpu_selector::operator()(const device &dev) const {
  int Score = REJECT_DEVICE_SCORE;
 
  if (dev.is_gpu()) {
    // device::get_devices returns filtered list of devices.
    Score = 1000;
    // Give preference to device of SYCL BE.
    if (isDeviceOfPreferredSyclBe(dev))
      Score += 50;
  }
  return Score;
}
 
int cpu_selector::operator()(const device &dev) const {
  int Score = REJECT_DEVICE_SCORE;
 
  if (dev.is_cpu()) {
    // device::get_devices returns filtered list of devices.
    Score = 1000;
 
    // Give preference to device of SYCL BE.
    if (isDeviceOfPreferredSyclBe(dev))
      Score += 50;
  }
  return Score;
}
 
int accelerator_selector::operator()(const device &dev) const {
  int Score = REJECT_DEVICE_SCORE;
 
  if (dev.is_accelerator()) {
    // device::get_devices returns filtered list of devices.
    Score = 1000;
 
    // Give preference to device of SYCL BE.
    if (isDeviceOfPreferredSyclBe(dev))
      Score += 50;
  }
  return Score;
}
 
int host_selector::operator()(const device &dev) const {
  int Score = REJECT_DEVICE_SCORE;
 
  if (dev.is_host()) {
    Score = 1000;
    // Give preference to device of SYCL BE.
    if (isDeviceOfPreferredSyclBe(dev))
      Score += 50;
  }
  return Score;
}
 
namespace ext {
namespace oneapi {
 
filter_selector::filter_selector(const std::string &Input)
    : impl(std::make_shared<detail::filter_selector_impl>(Input)) {}
 
int filter_selector::operator()(const device &Dev) const {
  return impl->operator()(Dev);
}
 
void filter_selector::reset() const { impl->reset(); }
 
device filter_selector::select_device() const {
  std::lock_guard<std::mutex> Guard(
      sycl::detail::GlobalHandler::instance().getFilterMutex());
 
  device Result = device_selector::select_device();
 
  reset();
 
  return Result;
}
 
} // namespace oneapi
} // namespace ext
 
namespace __SYCL2020_DEPRECATED("use 'ext::oneapi' instead") ONEAPI {
  using namespace ext::oneapi;
  filter_selector::filter_selector(const std::string &Input)
      : ext::oneapi::filter_selector(Input) {}
 
  int filter_selector::operator()(const device &Dev) const {
    return ext::oneapi::filter_selector::operator()(Dev);
  }
 
  void filter_selector::reset() const { ext::oneapi::filter_selector::reset(); }
 
  device filter_selector::select_device() const {
    return ext::oneapi::filter_selector::select_device();
  }
} // namespace ONEAPI
} // namespace sycl
} // __SYCL_INLINE_NAMESPACE(cl)