diff options
Diffstat (limited to 'src/runtime/mem_linux.go')
| -rw-r--r-- | src/runtime/mem_linux.go | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/src/runtime/mem_linux.go b/src/runtime/mem_linux.go index 7aa48170a1..845f72ded2 100644 --- a/src/runtime/mem_linux.go +++ b/src/runtime/mem_linux.go @@ -5,6 +5,7 @@ package runtime import ( + "runtime/internal/atomic" "runtime/internal/sys" "unsafe" ) @@ -34,10 +35,12 @@ func sysAlloc(n uintptr, sysStat *uint64) unsafe.Pointer { return p } +var adviseUnused = uint32(_MADV_FREE) + func sysUnused(v unsafe.Pointer, n uintptr) { // By default, Linux's "transparent huge page" support will // merge pages into a huge page if there's even a single - // present regular page, undoing the effects of the DONTNEED + // present regular page, undoing the effects of madvise(adviseUnused) // below. On amd64, that means khugepaged can turn a single // 4KB page to 2MB, bloating the process's RSS by as much as // 512X. (See issue #8832 and Linux kernel bug @@ -102,7 +105,13 @@ func sysUnused(v unsafe.Pointer, n uintptr) { throw("unaligned sysUnused") } - madvise(v, n, _MADV_DONTNEED) + advise := atomic.Load(&adviseUnused) + if errno := madvise(v, n, int32(advise)); advise == _MADV_FREE && errno != 0 { + // MADV_FREE was added in Linux 4.5. Fall back to MADV_DONTNEED if it is + // not supported. + atomic.Store(&adviseUnused, _MADV_DONTNEED) + madvise(v, n, _MADV_DONTNEED) + } } func sysUsed(v unsafe.Pointer, n uintptr) { |