Internally measure isolate uptime with monotonic time.

runtime/vm/pages.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 686 matching lines @@
   JSONObject space(object, "old");
   space.AddProperty("type", "HeapSpace");
   space.AddProperty("name", "old");
   space.AddProperty("vmName", "PageSpace");
   space.AddProperty("collections", collections());
   space.AddProperty64("used", UsedInWords() * kWordSize);
   space.AddProperty64("capacity", CapacityInWords() * kWordSize);
   space.AddProperty64("external", ExternalInWords() * kWordSize);
   space.AddProperty("time", MicrosecondsToSeconds(gc_time_micros()));
   if (collections() > 0) {
-    int64_t run_time = OS::GetCurrentTimeMicros() - isolate->start_time();
+    int64_t run_time = isolate->UptimeMicros();
     run_time = Utils::Maximum(run_time, static_cast<int64_t>(0));
     double run_time_millis = MicrosecondsToMilliseconds(run_time);
     double avg_time_between_collections =
         run_time_millis / static_cast<double>(collections());
     space.AddProperty("avgCollectionPeriodMillis",
                       avg_time_between_collections);
   } else {
     space.AddProperty("avgCollectionPeriodMillis", 0.0);
   }
 }
@@ skipping 419 matching lines @@
       Utils::Maximum<intptr_t>(0, capacity_increase_in_words);
   capacity_increase_in_words =
       Utils::RoundUp(capacity_increase_in_words, PageSpace::kPageSizeInWords);
   intptr_t capacity_increase_in_pages =
       capacity_increase_in_words / PageSpace::kPageSizeInWords;
   double multiplier = 1.0;
   // To avoid waste, the first GC should be triggered before too long. After
   // kInitialTimeoutSeconds, gradually lower the capacity limit.
   static const double kInitialTimeoutSeconds = 1.00;
   if (history_.IsEmpty()) {
-    double seconds_since_init = MicrosecondsToSeconds(
-        OS::GetCurrentTimeMicros() - heap_->isolate()->start_time());
+    double seconds_since_init =
+        MicrosecondsToSeconds(heap_->isolate()->UptimeMicros());
     if (seconds_since_init > kInitialTimeoutSeconds) {
       multiplier *= seconds_since_init / kInitialTimeoutSeconds;
     }
   }
   bool needs_gc = capacity_increase_in_pages * multiplier > grow_heap_;
   if (FLAG_log_growth) {
     OS::PrintErr("%s: %" Pd " * %f %s %" Pd "\n",
                  needs_gc ? "NEEDS GC" : "grow", capacity_increase_in_pages,
                  multiplier, needs_gc ? ">" : "<=", grow_heap_);
   }
@@ skipping 102 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result = static_cast<int>(
         (static_cast<double>(gc_time) / static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart