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Use madvise() for mmaped file advise (#10170) 

Summary:
A recent PR https://github.com/facebook/rocksdb/pull/10142 enabled fadvise for mmaped file. However, we were told that it might not take effective and madvise() should be used.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/10170

Test Plan:
Run existing tests
Run a benchmark using mmap with advise random and see I/O size is indeed small.

Reviewed By: anand1976

Differential Revision: D37158582

fbshipit-source-id: 8b3a74f0e89d2e16aac78ee4124c05841d4135c3
This commit is contained in:
sdong 2022-06-15 13:05:58 -07:00 committed by Facebook GitHub Bot
parent ce419c0f10
commit 69a32eecab
1 changed files with 51 additions and 18 deletions
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69
env/io_posix.cc vendored
View File

@ -88,22 +88,17 @@ int Fadvise(int fd, off_t offset, size_t len, int advice) {
#endif
}
int FadviseForHint(int fd, FSRandomAccessFile::AccessPattern pattern) {
switch (pattern) {
case FSRandomAccessFile::AccessPattern::kNormal:
return Fadvise(fd, 0, 0, POSIX_FADV_NORMAL);
case FSRandomAccessFile::AccessPattern::kRandom:
return Fadvise(fd, 0, 0, POSIX_FADV_RANDOM);
case FSRandomAccessFile::AccessPattern::kSequential:
return Fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
case FSRandomAccessFile::AccessPattern::kWillNeed:
return Fadvise(fd, 0, 0, POSIX_FADV_WILLNEED);
case FSRandomAccessFile::AccessPattern::kWontNeed:
return Fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
default:
assert(false);
return 1;
}
// A wrapper for fadvise, if the platform doesn't support fadvise,
// it will simply return 0.
int Madvise(void* addr, size_t len, int advice) {
#ifdef OS_LINUX
return posix_madvise(addr, len, advice);
#else
(void)addr;
(void)len;
(void)advice;
return 0; // simply do nothing.
#endif
}
namespace {
@ -839,7 +834,26 @@ void PosixRandomAccessFile::Hint(AccessPattern pattern) {
if (use_direct_io()) {
return;
}
FadviseForHint(fd_, pattern);
switch (pattern) {
case kNormal:
Fadvise(fd_, 0, 0, POSIX_FADV_NORMAL);
break;
case kRandom:
Fadvise(fd_, 0, 0, POSIX_FADV_RANDOM);
break;
case kSequential:
Fadvise(fd_, 0, 0, POSIX_FADV_SEQUENTIAL);
break;
case kWillNeed:
Fadvise(fd_, 0, 0, POSIX_FADV_WILLNEED);
break;
case kWontNeed:
Fadvise(fd_, 0, 0, POSIX_FADV_DONTNEED);
break;
default:
assert(false);
break;
}
}
IOStatus PosixRandomAccessFile::InvalidateCache(size_t offset, size_t length) {
@ -982,7 +996,26 @@ IOStatus PosixMmapReadableFile::Read(uint64_t offset, size_t n,
}
void PosixMmapReadableFile::Hint(AccessPattern pattern) {
FadviseForHint(fd_, pattern);
switch (pattern) {
case kNormal:
Madvise(mmapped_region_, length_, POSIX_MADV_NORMAL);
break;
case kRandom:
Madvise(mmapped_region_, length_, POSIX_MADV_RANDOM);
break;
case kSequential:
Madvise(mmapped_region_, length_, POSIX_MADV_SEQUENTIAL);
break;
case kWillNeed:
Madvise(mmapped_region_, length_, POSIX_MADV_WILLNEED);
break;
case kWontNeed:
Madvise(mmapped_region_, length_, POSIX_MADV_DONTNEED);
break;
default:
assert(false);
break;
}
}
IOStatus PosixMmapReadableFile::InvalidateCache(size_t offset, size_t length) {