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149 lines (117 loc) · 3.69 KB
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/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <folly/BenchmarkUtil.h>
#include <array> // @manual
#include <filesystem>
#include <fstream>
#include <string>
#include <fmt/format.h>
#include <folly/lang/Align.h>
#include <folly/portability/Sched.h>
#include <folly/portability/Windows.h>
#include <folly/system/arch/x86.h>
#if defined(__APPLE__) || defined(__FreeBSD__)
#include <sys/sysctl.h>
#endif
namespace folly {
namespace detail {
size_t bm_llc_size_fallback() {
#if defined(__linux__)
/// sysctl is deprecated on Linux; walk sysfs
int cpu = sched_getcpu();
if (cpu < 0) {
return 0;
}
auto dir = std::filesystem::path(
fmt::format("/sys/devices/system/cpu/cpu{}/cache", cpu));
size_t size = 0;
for (const auto& entry : std::filesystem::directory_iterator(dir)) {
if (entry.path().filename().native().starts_with("index")) {
std::ifstream size_ifs(entry.path() / "size");
std::string size_str;
size_ifs >> size_str;
size_t size_num = std::stoul(size_str);
if (size_str.back() == 'K') {
size_num *= 1024;
} else if (size_str.back() == 'M') {
size_num *= 1024 * 1024;
}
size = std::max(size, size_num);
}
}
return size;
#elif defined(__APPLE__) || defined(__FreeBSD__)
auto names = std::array{
"hw.l3cachesize", // FreeBSD, Intel Mac
"hw.l2cachesize", // Apple Silicon
};
for (auto name : names) {
uint64_t size = 0;
size_t len = sizeof(size);
if (sysctlbyname(name, &size, &len, NULL, 0) == 0 && size > 0) {
return size;
}
}
return 0;
#elif defined(_WIN32)
DWORD length = 0;
GetLogicalProcessorInformation(nullptr, &length);
if (GetLastError() != ERROR_INSUFFICIENT_BUFFER || length == 0) {
return 0;
}
if (length % sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION) != 0) {
return 0;
}
size_t const count = length / sizeof(SYSTEM_LOGICAL_PROCESSOR_INFORMATION);
std::vector<SYSTEM_LOGICAL_PROCESSOR_INFORMATION> infos(count);
if (!GetLogicalProcessorInformation(infos.data(), &length)) {
return 0;
}
size_t size = 0;
for (auto const& info : infos) {
if (info.Relationship == RelationCache) {
size = std::max<size_t>(size, info.Cache.Size);
}
}
return size;
#else
return 0;
#endif
}
} // namespace detail
size_t bm_llc_size() {
return kIsArchX86 || kIsArchAmd64
? folly::x86_cpuid_get_llc_cache_info().cache_size()
: detail::bm_llc_size_fallback();
}
void bm_llc_evict(size_t value) {
constexpr auto step =
folly::hardware_constructive_interference_size / sizeof(size_t);
constexpr auto words_per_line =
folly::hardware_constructive_interference_size / step;
static auto const llc_size = bm_llc_size();
auto const llc_lines =
llc_size / folly::hardware_constructive_interference_size;
static std::unique_ptr<size_t volatile[]> const vec{
new size_t[llc_lines * words_per_line]};
// do N passes over the region, each time touching one word per line
for (size_t j = 0; j < step; ++j) {
for (size_t i = 0; i < llc_lines; i += step) {
vec[i * words_per_line + j] = value;
}
}
}
} // namespace folly