pitrou commented on a change in pull request #7172:
URL: https://github.com/apache/arrow/pull/7172#discussion_r425997507
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File path: cpp/src/arrow/util/io_util.cc
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@@ -1072,6 +1072,61 @@ Status MemoryMapRemap(void* addr, size_t old_size,
size_t new_size, int fildes,
#endif
}
+Status MemoryAdviseWillNeed(const std::vector<MemoryRegion>& regions) {
+ const auto page_size = static_cast<size_t>(GetPageSize());
+ DCHECK_GT(page_size, 0);
+ const size_t page_mask = ~(page_size - 1);
+ DCHECK_EQ(page_mask & page_size, page_size);
+
+ auto align_region = [=](const MemoryRegion& region) -> MemoryRegion {
+ const auto addr = reinterpret_cast<uintptr_t>(region.addr);
+ const auto aligned_addr = addr & page_mask;
+ DCHECK_LT(addr - aligned_addr, page_size);
+ return {reinterpret_cast<void*>(aligned_addr),
+ region.size + static_cast<size_t>(addr - aligned_addr)};
+ };
+
+#ifdef _WIN32
+ // PrefetchVirtualMemory() is available on Windows 8 or later
+ struct PrefetchEntry { // Like WIN32_MEMORY_RANGE_ENTRY
+ void* VirtualAddress;
+ size_t NumberOfBytes;
+
+ PrefetchEntry(const MemoryRegion& region) // NOLINT runtime/explicit
+ : VirtualAddress(region.addr), NumberOfBytes(region.size) {}
+ };
+ using PrefetchVirtualMemoryFunc = BOOL (*)(HANDLE, ULONG_PTR,
PrefetchEntry*, ULONG);
+ static const auto prefetch_virtual_memory =
reinterpret_cast<PrefetchVirtualMemoryFunc>(
+ GetProcAddress(GetModuleHandleW(L"kernel32.dll"),
"PrefetchVirtualMemory"));
Review comment:
Right. In a couple of years we can probably drop Windows 7
compatibility...
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