Store the last value for extremas too, since we don't see all values …

…otherwise
schmelter-sap · Jul 7, 2023 · 86ff458 · 86ff458
1 parent 363d46a
commit 86ff458
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Showing 2 changed files with 28 additions and 12 deletions.
diff --git a/src/hotspot/share/runtime/globals.hpp b/src/hotspot/share/runtime/globals.hpp
@@ -522,9 +522,9 @@ const int ObjectAlignmentInBytes = 8;
   product(bool, PrintVitalsAtExit, false,                                   \
           "Prints vitals at VM exit to tty.")                               \
                                                                             \
-  product(bool, StorePeakSamples, true,                                     \
-          "If enabled we store the samples for peak values of selected "    \
-          "types.")                                                         \
+  product(bool, StoreVitalsExtremas, true,                                  \
+          "If enabled we store the samples for extremum values of "         \
+          "selected types.")                                                \
                                                                             \
   product(ccstr, VitalsFile, NULL,                                          \
           "When DumpVitalsAtExit is set, the file name prefix for the "     \

diff --git a/src/hotspot/share/vitals/vitals.cpp b/src/hotspot/share/vitals/vitals.cpp
@@ -773,12 +773,13 @@ class SampleTables : public CHeapObj<mtInternal> {
   SampleTable _short_term_table;
   SampleTable _long_term_table;
   Sample*     _extremum_samples;
+  Sample*     _last_extremum_samples;
 
   int _count;
 
   // A pre-allocated buffer for printing reports. We preallocate this since
   // when we want to print the report we may be in no condition to allocate memory.
-  char _temp_buffer[196 * K];
+  char _temp_buffer[512 * K];
 
   static void print_table(const SampleTable* table, outputStream* st,
     const ColumnWidths* widths, const print_info_t* pi) {
@@ -823,6 +824,7 @@ class SampleTables : public CHeapObj<mtInternal> {
     : _short_term_table(short_term_tablesize()),
     _long_term_table(long_term_tablesize),
     _extremum_samples(NULL),
+    _last_extremum_samples(NULL),
     _count(0)
   {}
 
@@ -839,13 +841,21 @@ class SampleTables : public CHeapObj<mtInternal> {
       _long_term_table.add_sample(sample);
     }
 
-    // Update peak samples if needed.
-    if (StorePeakSamples) {
-      if (_extremum_samples == NULL) {
-        // For the first sample just initialize with the sample for all values we store peaks for.
+    // Update exetremum samples if needed.
+    if (StoreVitalsExtremas) {
+      static Sample* last_sample = NULL;
+
+      if (last_sample == NULL) {
+        // Nothing to do yet. We need at least two samples to handle all values in the sample. Just
+        // allocate the space for the last sample as a marker.
+        last_sample = (Sample*) NEW_C_HEAP_ARRAY(char, Sample::size_in_bytes(), mtInternal);
+      } else if (_extremum_samples == NULL) {
+        // Allocate the two array and initialize it with the first possible samples.
         _extremum_samples = (Sample*)NEW_C_HEAP_ARRAY(char, Sample::size_in_bytes() * Sample::num_values(), mtInternal);
+        _last_extremum_samples = (Sample*) NEW_C_HEAP_ARRAY(char, Sample::size_in_bytes() * Sample::num_values(), mtInternal);
 
         for (int i = 0; i < Sample::num_values(); ++i) {
+          ::memcpy(i * Sample::size_in_bytes() + (char*) _last_extremum_samples, last_sample, Sample::size_in_bytes());
           ::memcpy(i * Sample::size_in_bytes() + (char*) _extremum_samples, sample, Sample::size_in_bytes());
         }
       }
@@ -854,17 +864,22 @@ class SampleTables : public CHeapObj<mtInternal> {
         for (Column const* column = ColumnList::the_list()->first(); column != NULL; column = column->next()) {
           if (column->extremum() != NONE) {
             int idx = column->index();
-            Sample* extremum_sample = (Sample*)(idx * Sample::size_in_bytes() + (char*) _extremum_samples);
+            Sample* extremum_sample = (Sample*) (idx * Sample::size_in_bytes() + (char*) _extremum_samples);
+            Sample* last_extremum_sample = (Sample*) (idx * Sample::size_in_bytes() + (char*) _last_extremum_samples);
 
             bool should_log = (column->extremum() == MAX) && (sample->value(idx) > extremum_sample->value(idx));
             should_log |= (column->extremum() == MIN) && (sample->value(idx) < extremum_sample->value(idx));
 
             if (should_log) {
+              ::memcpy(last_extremum_sample, last_sample, Sample::size_in_bytes());
               ::memcpy(extremum_sample, sample, Sample::size_in_bytes());
             }
           }
         }
       }
+
+      // Remember the last sample.
+      ::memcpy(last_sample, sample, Sample::size_in_bytes());
     }
   }
 
@@ -911,14 +926,15 @@ class SampleTables : public CHeapObj<mtInternal> {
         st->cr();
       }
 
-      if (StorePeakSamples) {
+      if (StoreVitalsExtremas && (_extremum_samples != NULL) && (_last_extremum_samples != NULL)) {
         st->print_cr("Samples at extremes (+ marks a maximum, - marks a minimum)");
         print_headers(st, &widths, pi, 1); // Need more space for the mark to display.
 
         for (Column const* column = ColumnList::the_list()->first(); column != NULL; column = column->next()) {
           if (column->extremum() != NONE) {
-            Sample* peak_sample = (Sample*) (column->index() * Sample::size_in_bytes() + (char*) _extremum_samples);
-            print_one_sample(st, peak_sample, NULL, &widths, pi, column->index(), column->extremum() == MIN ? '-' : '+');
+            Sample* extremum_sample = (Sample*) (column->index() * Sample::size_in_bytes() + (char*) _extremum_samples);
+            Sample* last_extremum_sample = (Sample*) (column->index() * Sample::size_in_bytes() + (char*) _last_extremum_samples);
+            print_one_sample(st, extremum_sample, last_extremum_sample, &widths, pi, column->index(), column->extremum() == MIN ? '-' : '+');
           }
         }
       }