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[host_memory] decrease latency of mapping on linux #232

Merged
Shinmegumi merged 1 commit from memlatencydecmap into master 2025-09-17 02:31:45 +02:00
Conversation 4 Commits 1 Files changed 1 +11 -6
1 changed files with 11 additions and 6 deletions
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17
src/common/host_memory.cpp
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@ -598,12 +598,17 @@ public:
bool ClearBackingRegion(size_t physical_offset, size_t length) {
#ifdef __linux__
// Set MADV_REMOVE on backing map to destroy it instantly.
// This also deletes the area from the backing file.
int ret = madvise(backing_base + physical_offset, length, MADV_REMOVE);
ASSERT_MSG(ret == 0, "madvise failed: {}", strerror(errno));
return true;
// Only incur syscall cost IF memset would be slower (theshold = 16MiB)
// TODO(lizzie): Smarter way to dynamically get this threshold (broadwell != raptor lake) for example
if (length >= 2097152UL * 8) {
// Set MADV_REMOVE on backing map to destroy it instantly.
// This also deletes the area from the backing file.
int ret = madvise(backing_base + physical_offset, length, MADV_REMOVE);
ASSERT_MSG(ret == 0, "madvise failed: {}", strerror(errno));
return true;
} else {
return false;
}
#else
return false;
#endif