[memory-infra] Implement peak detection logic

base/trace_event/memory_dump_scheduler.h

Index: base/trace_event/memory_dump_scheduler.h
diff --git a/base/trace_event/memory_dump_scheduler.h b/base/trace_event/memory_dump_scheduler.h
index 2214e053b46a3c4e16541b8b0bb66ecf4f412719..9fc7ee9819dca093f744a92d06d8971f79fd0e56 100644
--- a/base/trace_event/memory_dump_scheduler.h
+++ b/base/trace_event/memory_dump_scheduler.h
@@ -5,6 +5,8 @@
 #ifndef BASE_TRACE_EVENT_MEMORY_DUMP_SCHEDULER_H
 #define BASE_TRACE_EVENT_MEMORY_DUMP_SCHEDULER_H
 
+#include <deque>
+
 #include "base/base_export.h"
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
@@ -85,6 +87,8 @@ class BASE_EXPORT MemoryDumpScheduler {
     int num_polls_from_last_dump;
 
     uint64_t last_dump_memory_total;
+    int64_t memory_increase_threshold;
+    std::deque<uint64_t> last_n_memory_totals;

[Primiano Tucci (use gerrit), 2017/03/09 18:31:27]

I'd drop the "_n" in the name

[Primiano Tucci (use gerrit), 2017/03/09 18:31:27]

also deque is super silly memory-wise, as dskiba found out, in some platforms
allocated 4k pages, which is a waste here.
I think a better approach here would be:
- Have a flat array uint32_t
last_memory_samples[kNumTotalsTrackedForPeakDetection];
- Have a uint32_t last_memory_samples_index;

When you write them in the buffer just do:
last_memory_samples[index] = GetMemory()
index = (index + 1) % kNumTotals
 
When you compute the average/stddev just exclude the values with 0, because you
know that 0 is never a valid value.

[ssid, 2017/03/09 19:32:44]

I didn't want to re-implement deque here and code looks complicated. It will
save few hundred bytes i guess.

[ssid, 2017/03/09 19:32:44]

Done.

 
     DISALLOW_COPY_AND_ASSIGN(PollingTriggerState);
   };
@@ -101,6 +105,9 @@ class BASE_EXPORT MemoryDumpScheduler {
   // Returns true if peak memory value is detected.
   bool ShouldTriggerDump(uint64_t current_memory_total);
 
+  // Helper to detect peaks in memory usage.
+  bool IsCurrentSamplePeak(uint64_t current_memory_total);
+
   // Must be set before enabling tracing.
   static void SetPollingIntervalForTesting(uint32_t interval);
 
@@ -112,6 +119,9 @@ class BASE_EXPORT MemoryDumpScheduler {
   PeriodicTriggerState periodic_state_;
   PollingTriggerState polling_state_;
 
+  // Total physical memory of the device.
+  size_t total_physical_memory_;

[Primiano Tucci (use gerrit), 2017/03/09 18:31:27]

I find this a bit of a misleading name, because I can't tell whether this is the
"total amount of system memory"  or "amount of system memory used" or "total
memory used by chrome". I think the 1st, but would be great to  clarify.

[ssid, 2017/03/09 19:32:44]

sorry, mistake. Removed this field.

+
   DISALLOW_COPY_AND_ASSIGN(MemoryDumpScheduler);
 };