4 files changed, 24 insertions, 10 deletions
diff --git a/vespamalloc/src/tests/stacktrace/stacktrace.cpp b/vespamalloc/src/tests/stacktrace/stacktrace.cpp
index d7f7d45656d..2592222fce3 100644
--- a/vespamalloc/src/tests/stacktrace/stacktrace.cpp
+++ b/vespamalloc/src/tests/stacktrace/stacktrace.cpp
@@ -29,7 +29,7 @@ void verify_that_vespamalloc_datasegment_size_exists() {
     assert(info.ordblks == 0);
     assert(info.smblks == 0);
     assert(info.uordblks > 0);
-    assert(info.usmblks == 0);
+    assert(info.usmblks > 0);
 #else
     struct mallinfo info = mallinfo();
     printf("Malloc used %dm of memory\n",info.arena);
@@ -43,7 +43,7 @@ void verify_that_vespamalloc_datasegment_size_exists() {
     assert(info.ordblks == 0);
     assert(info.smblks == 0);
     assert(info.uordblks > 0);
-    assert(info.usmblks == 0);
+    assert(info.usmblks > 0);
 #endif
 }
 
diff --git a/vespamalloc/src/vespamalloc/malloc/mmappool.cpp b/vespamalloc/src/vespamalloc/malloc/mmappool.cpp
index e43ea2e8342..cee709ed0ed 100644
--- a/vespamalloc/src/vespamalloc/malloc/mmappool.cpp
+++ b/vespamalloc/src/vespamalloc/malloc/mmappool.cpp
@@ -10,6 +10,8 @@ namespace vespamalloc {
 MMapPool::MMapPool()
     : _page_size(getpagesize()),
       _huge_flags((getenv("VESPA_USE_HUGEPAGES") != nullptr) ? MAP_HUGETLB : 0),
+      _peakBytes(0ul),
+      _currentBytes(0ul),
       _count(0),
       _mutex(),
       _mappings()
@@ -28,9 +30,13 @@ MMapPool::getNumMappings() const {
 size_t
 MMapPool::getMmappedBytes() const {
     std::lock_guard guard(_mutex);
-    size_t sum(0);
-    std::for_each(_mappings.begin(), _mappings.end(), [&sum](const auto & e){ sum += e.second._sz; });
-    return sum;
+    return _currentBytes;
+}
+
+size_t
+MMapPool::getMmappedBytesPeak() const {
+    std::lock_guard guard(_mutex);
+    return _peakBytes;
 }
 
 void *
@@ -76,10 +82,10 @@ MMapPool::mmap(size_t sz) {
         std::lock_guard guard(_mutex);
         auto [it, inserted] = _mappings.insert(std::make_pair(buf, MMapInfo(mmapId, sz)));
         ASSERT_STACKTRACE(inserted);
+        _currentBytes += sz;
+        _peakBytes = std::max(_peakBytes, _currentBytes);
         if (sz >= _G_bigBlockLimit) {
-            size_t sum(0);
-            std::for_each(_mappings.begin(), _mappings.end(), [&sum](const auto & e){ sum += e.second._sz; });
-            fprintf(_G_logFile, "%ld mappings of accumulated size %ld\n", _mappings.size(), sum);
+            fprintf(_G_logFile, "%ld mappings of accumulated size %ld\n", _mappings.size(), _currentBytes);
         }
     }
     return buf;
@@ -98,6 +104,7 @@ MMapPool::unmap(void * ptr) {
         }
         sz = found->second._sz;
         _mappings.erase(found);
+        _currentBytes -= sz;
     }
     int munmap_ok = ::munmap(ptr, sz);
     ASSERT_STACKTRACE(munmap_ok == 0);
diff --git a/vespamalloc/src/vespamalloc/malloc/mmappool.h b/vespamalloc/src/vespamalloc/malloc/mmappool.h
index c0b73c56e4e..0a3dd5d0a0a 100644
--- a/vespamalloc/src/vespamalloc/malloc/mmappool.h
+++ b/vespamalloc/src/vespamalloc/malloc/mmappool.h
@@ -19,6 +19,7 @@ public:
     size_t get_size(void *) const;
     size_t getNumMappings() const;
     size_t getMmappedBytes() const;
+    size_t getMmappedBytesPeak() const;
     void info(FILE * os, size_t level) const;
 private:
     struct MMapInfo {
@@ -28,6 +29,8 @@ private:
     };
     const size_t        _page_size;
     const int           _huge_flags;
+    size_t              _peakBytes;
+    size_t              _currentBytes;
     std::atomic<size_t> _count;
     std::atomic<bool>   _has_hugepage_failure_just_happened;
     mutable std::mutex  _mutex;
diff --git a/vespamalloc/src/vespamalloc/malloc/overload.h b/vespamalloc/src/vespamalloc/malloc/overload.h
index cb57e6b2fa8..bf9710b9b32 100644
--- a/vespamalloc/src/vespamalloc/malloc/overload.h
+++ b/vespamalloc/src/vespamalloc/malloc/overload.h
@@ -119,7 +119,9 @@ struct mallinfo2 mallinfo2() __THROW {
     info.smblks = 0;
     info.hblkhd = vespamalloc::_GmemP->mmapPool().getNumMappings();
     info.hblks = vespamalloc::_GmemP->mmapPool().getMmappedBytes();
-    info.usmblks = 0;
+    size_t highwaterMark = vespamalloc::_GmemP->dataSegment().dataSize() +
+                           vespamalloc::_GmemP->mmapPool().getMmappedBytesPeak();
+    info.usmblks = highwaterMark;
     info.fsmblks = 0;
     info.fordblks = vespamalloc::_GmemP->dataSegment().freeSize();
     info.uordblks = info.arena + info.hblks - info.fordblks;
@@ -135,7 +137,9 @@ struct mallinfo mallinfo() __THROW {
     info.smblks = 0;
     info.hblkhd = vespamalloc::_GmemP->mmapPool().getNumMappings();
     info.hblks = (vespamalloc::_GmemP->mmapPool().getMmappedBytes() >> 20);
-    info.usmblks = 0;
+    size_t highwaterMark = vespamalloc::_GmemP->dataSegment().dataSize() +
+                           vespamalloc::_GmemP->mmapPool().getMmappedBytesPeak();
+    info.usmblks = (highwaterMark >> 20);
     info.fsmblks = 0;
     info.fordblks = (vespamalloc::_GmemP->dataSegment().freeSize() >> 20);
     info.uordblks = info.arena + info.hblks - info.fordblks;