8332237: [nmt] Remove the need for ThreadStackTracker::track_as_vm()

Reviewed-by: jsjolen, azafari

src/hotspot/share/nmt/memBaseline.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -151,11 +151,6 @@ bool MemBaseline::baseline_allocation_sites() {
     return false;
   }
 
-  // Walk simple thread stacks
-  if (!ThreadStackTracker::walk_simple_thread_stack_site(&malloc_walker)) {
-    return false;
-  }
-
   _malloc_sites.move(malloc_walker.malloc_sites());
   // The malloc sites are collected in size order
   _malloc_sites_order = by_size;

src/hotspot/share/nmt/memReporter.cpp

@@ -193,17 +193,10 @@ void MemSummaryReporter::report_summary_of_type(MEMFLAGS flag,
 
   // Count thread's native stack in "Thread" category
   if (flag == mtThread) {
-    if (ThreadStackTracker::track_as_vm()) {
     const VirtualMemory* thread_stack_usage =
       (const VirtualMemory*)_vm_snapshot->by_type(mtThreadStack);
     reserved_amount  += thread_stack_usage->reserved();
     committed_amount += thread_stack_usage->committed();
-    } else {
-      const MallocMemory* thread_stack_usage =
-        (const MallocMemory*)_malloc_snapshot->by_type(mtThreadStack);
-      reserved_amount += thread_stack_usage->malloc_size();
-      committed_amount += thread_stack_usage->malloc_size();
-    }
   } else if (flag == mtNMT) {
     // Count malloc headers in "NMT" category
     reserved_amount  += _malloc_snapshot->malloc_overhead();
@@ -240,21 +233,12 @@ void MemSummaryReporter::report_summary_of_type(MEMFLAGS flag,
     out->print_cr("%27s (  instance classes #" SIZE_FORMAT ", array classes #" SIZE_FORMAT ")",
       " ", _instance_class_count, _array_class_count);
   } else if (flag == mtThread) {
-    if (ThreadStackTracker::track_as_vm()) {
     const VirtualMemory* thread_stack_usage =
      _vm_snapshot->by_type(mtThreadStack);
     // report thread count
     out->print_cr("%27s (threads #" SIZE_FORMAT ")", " ", ThreadStackTracker::thread_count());
     out->print("%27s (stack: ", " ");
     print_total(thread_stack_usage->reserved(), thread_stack_usage->committed(), thread_stack_usage->peak_size());
-    } else {
-      MallocMemory* thread_stack_memory = _malloc_snapshot->by_type(mtThreadStack);
-      const char* scale = current_scale();
-      // report thread count
-      out->print_cr("%27s (threads #" SIZE_FORMAT ")", " ", thread_stack_memory->malloc_count());
-      out->print("%27s (Stack: " SIZE_FORMAT "%s", " ",
-        amount_in_current_scale(thread_stack_memory->malloc_size()), scale);
-    }
     out->print_cr(")");
   }
 
@@ -627,7 +611,6 @@ void MemSummaryDiffReporter::diff_summary_of_type(MEMFLAGS flag,
       out->print_cr(")");
 
       out->print("%27s (stack: ", " ");
-      if (ThreadStackTracker::track_as_vm()) {
       // report thread stack
       const VirtualMemory* current_thread_stack =
         _current_baseline.virtual_memory(mtThreadStack);
@@ -636,15 +619,7 @@ void MemSummaryDiffReporter::diff_summary_of_type(MEMFLAGS flag,
 
       print_virtual_memory_diff(current_thread_stack->reserved(), current_thread_stack->committed(),
         early_thread_stack->reserved(), early_thread_stack->committed());
-      } else {
-        const MallocMemory* current_thread_stack =
-          _current_baseline.malloc_memory(mtThreadStack);
-        const MallocMemory* early_thread_stack =
-          _early_baseline.malloc_memory(mtThreadStack);
 
-        print_malloc_diff(current_thread_stack->malloc_size(), current_thread_stack->malloc_count(),
-          early_thread_stack->malloc_size(), early_thread_stack->malloc_count(), flag);
-      }
       out->print_cr(")");
     }
 

src/hotspot/share/nmt/memTracker.cpp

@@ -67,8 +67,7 @@ void MemTracker::initialize() {
 
   if (level > NMT_off) {
     if (!MallocTracker::initialize(level) ||
-        !VirtualMemoryTracker::initialize(level) ||
+        !VirtualMemoryTracker::initialize(level)) {
-        !ThreadStackTracker::initialize(level)) {
       assert(false, "NMT initialization failed");
       level = NMT_off;
       log_warning(nmt)("NMT initialization failed. NMT disabled.");

src/hotspot/share/nmt/nmtUsage.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -43,14 +43,12 @@ NMTUsage::NMTUsage(NMTUsageOptions options) :
     _usage_options(options) { }
 
 void NMTUsage::walk_thread_stacks() {
-  // If backed by virtual memory, snapping the thread stacks involves walking
+  // Snapping the thread stacks involves walking the areas to figure out how
-  // them to to figure out how much memory is committed if they are backed by
+  // much memory had been committed if they are backed by virtual memory. This
-  // virtual memory. This needs ot happen before we take the snapshot of the
+  // needs to happen before we take the snapshot of the virtual memory since it
-  // virtual memory since it will update this information.
+  // will update this information.
-  if (ThreadStackTracker::track_as_vm()) {
   VirtualMemoryTracker::snapshot_thread_stacks();
 }
-}
 
 void NMTUsage::update_malloc_usage() {
   // Thread critical needed keep values in sync, total area size

src/hotspot/share/nmt/threadStackTracker.cpp

@@ -1,5 +1,6 @@
 /*
- * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2019, 2024, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,95 +25,46 @@
 
 #include "precompiled.hpp"
 
-#include "nmt/mallocTracker.hpp"
 #include "nmt/memTracker.hpp"
 #include "nmt/threadStackTracker.hpp"
 #include "nmt/virtualMemoryTracker.hpp"
+#include "runtime/os.hpp"
 #include "runtime/threadCritical.hpp"
+#include "utilities/align.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
 
 volatile size_t ThreadStackTracker::_thread_count = 0;
-SortedLinkedList<SimpleThreadStackSite, ThreadStackTracker::compare_thread_stack_base>* ThreadStackTracker::_simple_thread_stacks = nullptr;
 
-bool ThreadStackTracker::initialize(NMT_TrackingLevel level) {
+static void align_thread_stack_boundaries_inward(void*& base, size_t& size) {
-  if (level == NMT_detail && !track_as_vm()) {
+  // Thread stack boundaries don't have to be aligned to page boundaries. For cases where they
-    _simple_thread_stacks = new (std::nothrow, mtNMT)
+  // are not aligned (e.g. AIX, Alpine), this function corrects boundaries inward to the next
-      SortedLinkedList<SimpleThreadStackSite, ThreadStackTracker::compare_thread_stack_base>();
+  // page boundaries. This ensures that we can track thread stacks piggybacking on the virtual
-    return (_simple_thread_stacks != nullptr);
+  // memory tracker.
-  }
+  void* const base_aligned = align_up(base, os::vm_page_size());
-  return true;
+  const size_t size_aligned = align_down(size, os::vm_page_size());
-}
+  assert(size_aligned > 0, "stack size less than a page?");
-
+  base = base_aligned;
-int ThreadStackTracker::compare_thread_stack_base(const SimpleThreadStackSite& s1, const SimpleThreadStackSite& s2) {
+  size = size_aligned;
-  return primitive_compare(s1.base(), s2.base());
 }
 
 void ThreadStackTracker::new_thread_stack(void* base, size_t size, const NativeCallStack& stack) {
-  assert(MemTracker::tracking_level() >= NMT_summary, "Must be");
+  assert(MemTracker::enabled(), "Must be");
   assert(base != nullptr, "Should have been filtered");
+  align_thread_stack_boundaries_inward(base, size);
+
   ThreadCritical tc;
-  if (track_as_vm()) {
   VirtualMemoryTracker::add_reserved_region((address)base, size, stack, mtThreadStack);
-  } else {
-    // Use a slot in mallocMemorySummary for thread stack bookkeeping
-    MallocMemorySummary::record_malloc(size, mtThreadStack);
-    if (MemTracker::tracking_level() == NMT_detail) {
-      assert(_simple_thread_stacks != nullptr, "Must be initialized");
-      SimpleThreadStackSite site((address)base, size, stack);
-      _simple_thread_stacks->add(site);
-    }
-  }
   _thread_count++;
 }
 
 void ThreadStackTracker::delete_thread_stack(void* base, size_t size) {
-  assert(MemTracker::tracking_level() >= NMT_summary, "Must be");
+  assert(MemTracker::enabled(), "Must be");
   assert(base != nullptr, "Should have been filtered");
+  align_thread_stack_boundaries_inward(base, size);
+
   ThreadCritical tc;
-  if(track_as_vm()) {
   VirtualMemoryTracker::remove_released_region((address)base, size);
-  } else {
-    // Use a slot in mallocMemorySummary for thread stack bookkeeping
-    MallocMemorySummary::record_free(size, mtThreadStack);
-    if (MemTracker::tracking_level() == NMT_detail) {
-      assert(_simple_thread_stacks != nullptr, "Must be initialized");
-      SimpleThreadStackSite site((address)base, size, NativeCallStack::empty_stack()); // Fake object just to serve as compare target for delete
-      bool removed = _simple_thread_stacks->remove(site);
-      assert(removed, "Must exist");
-    }
-  }
   _thread_count--;
 }
 
-bool ThreadStackTracker::walk_simple_thread_stack_site(MallocSiteWalker* walker) {
-  if (!track_as_vm()) {
-    LinkedListImpl<MallocSite> _sites;
-    {
-      ThreadCritical tc;
-      assert(_simple_thread_stacks != nullptr, "Must be initialized");
-      LinkedListIterator<SimpleThreadStackSite> itr(_simple_thread_stacks->head());
-      const SimpleThreadStackSite* ts = itr.next();
-      // Consolidate sites and convert to MallocSites, so we can piggyback into
-      // malloc snapshot
-      while (ts != nullptr) {
-        MallocSite site(*ts->call_stack(), mtThreadStack);
-        MallocSite* exist = _sites.find(site);
-        if (exist != nullptr) {
-          exist->allocate(ts->size());
-        } else {
-          site.allocate(ts->size());
-          _sites.add(site);
-        }
-        ts = itr.next();
-      }
-    }
-
-    // Piggyback to malloc snapshot
-    LinkedListIterator<MallocSite> site_itr(_sites.head());
-    const MallocSite* s = site_itr.next();
-    while (s != nullptr) {
-      walker->do_malloc_site(s);
-      s = site_itr.next();
-    }
-  }
-  return true;
-}

src/hotspot/share/nmt/threadStackTracker.hpp

@@ -1,5 +1,6 @@
 /*
- * Copyright (c) 2019, 2021, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2019, 2024, Red Hat, Inc. All rights reserved.
+ * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,61 +26,17 @@
 #ifndef SHARE_NMT_THREADSTACKTRACKER_HPP
 #define SHARE_NMT_THREADSTACKTRACKER_HPP
 
-#include "nmt/allocationSite.hpp"
+#include "memory/allStatic.hpp"
-#include "nmt/mallocSiteTable.hpp"
+#include "utilities/globalDefinitions.hpp"
-#include "nmt/nmtCommon.hpp"
-#include "utilities/linkedlist.hpp"
 #include "utilities/nativeCallStack.hpp"
 
-class SimpleThreadStackSite : public AllocationSite {
-  const address _base;
-  const size_t  _size;
-public:
-  SimpleThreadStackSite(address base, size_t size, const NativeCallStack& stack) :
-    AllocationSite(stack, mtThreadStack),
-    _base(base),
-    _size(size) {}
-
-  bool equals(const SimpleThreadStackSite& mts) const {
-    bool eq = base() == mts.base();
-    assert(!eq || size() == mts.size(), "Must match");
-    return eq;
-  }
-
-  size_t  size() const { return _size; }
-  address base() const { return _base; }
-};
-
-  /*
-   * Most of platforms, that hotspot support, have their thread stacks backed by
-   * virtual memory by default. For these cases, thread stack tracker simply
-   * delegates tracking to virtual memory tracker.
-   * However, there are exceptions, (e.g. AIX), that platforms can provide stacks
-   * that are not page aligned. A hypothetical VM implementation, it can provide
-   * it own stacks. In these case, track_as_vm() should return false and manage
-   * stack tracking by this tracker internally.
-   * During memory snapshot, tracked thread stacks memory data is walked and stored
-   * along with malloc'd data inside baseline. The regions are not scanned and assumed
-   * all committed for now. Can add scanning phase when there is a need.
-   */
 class ThreadStackTracker : AllStatic {
 private:
   static volatile size_t _thread_count;
-
-  static int compare_thread_stack_base(const SimpleThreadStackSite& s1, const SimpleThreadStackSite& s2);
-  static SortedLinkedList<SimpleThreadStackSite, compare_thread_stack_base>* _simple_thread_stacks;
 public:
-  static bool initialize(NMT_TrackingLevel level);
-
   static void new_thread_stack(void* base, size_t size, const NativeCallStack& stack);
   static void delete_thread_stack(void* base, size_t size);
-
-  static bool   track_as_vm()  { return AIX_ONLY(false) NOT_AIX(true); }
   static size_t thread_count() { return _thread_count; }
-
-  // Snapshot support. Piggyback thread stack data in malloc slot, NMT always handles
-  // thread stack slot specially since beginning.
-  static bool walk_simple_thread_stack_site(MallocSiteWalker* walker);
 };
 
 #endif // SHARE_NMT_THREADSTACKTRACKER_HPP

src/hotspot/share/nmt/virtualMemoryTracker.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -47,11 +47,8 @@ void VirtualMemory::update_peak(size_t size) {
 }
 
 void VirtualMemorySummary::snapshot(VirtualMemorySnapshot* s) {
-  // Only if thread stack is backed by virtual memory
-  if (ThreadStackTracker::track_as_vm()) {
   // Snapshot current thread stacks
   VirtualMemoryTracker::snapshot_thread_stacks();
-  }
   as_snapshot()->copy_to(s);
 }