Add madvise(buf, len, MADV_HUGEPAGE) call to signal that you strongly prefer huge pages.

This will make a difference if /sys/kernel/mm/transparent_hugepage/enabled has been set to [madvise], and not [always].

1 files changed, 3 insertions, 0 deletions

diff --git a/vespalib/src/vespa/vespalib/util/alloc.cpp b/vespalib/src/vespa/vespalib/util/alloc.cpp
index 3f49fc4b427..0f453111c72 100644
--- a/vespalib/src/vespa/vespalib/util/alloc.cpp
+++ b/vespalib/src/vespa/vespalib/util/alloc.cpp
@@ -353,6 +353,9 @@ MMapAllocator::salloc(size_t sz, void * wantedAddress)
             store_relaxed(_G_hasHugePageFailureJustHappened, false);
         }
 #ifdef __linux__
+        if (madvise(buf, sz, MADV_HUGEPAGE) != 0) {
+            // Just an advise, not everyone will listen...
+        }
         if (sz >= _G_MMapNoCoreLimit) {
             if (madvise(buf, sz, MADV_DONTDUMP) != 0) {
                 LOG(warning, "Failed madvise(%p, %ld, MADV_DONTDUMP) = '%s'", buf, sz, FastOS_FileInterface::getLastErrorString().c_str());