Increase kMaxEvents and error out when it's exceeded (#1835)

The current behavior silently resets and overwrites the internal list, this PR changes it to error out instead.

BUG=b/264555999

Author: paulinesho

tensorflow/lite/micro/docs/profiling.md

@@ -23,11 +23,14 @@ from within operator kernels and other TFLite Micro routines.
 
 ## API
 
-The MicroInterpreter class constructor contains and optional profiler argument.
+The MicroInterpreter class constructor contains an optional profiler argument.
 This profiler must be an instance of the tflite::Profiler class, and should
 implement the BeginEvent and EndEvent methods. There is a default implementation
 in tensorflow/lite/micro/micro_profiler.cc which can be used for most purposes.
 
+The best practice for profiling across multiple invocations is to reset or call
+`ClearEvents()` in between invocations.
+
 ## Per-Op Profiling
 
 There is a feature in the MicroInterpreter to enable per-op profiling. To enable

tensorflow/lite/micro/micro_profiler.cc

@@ -26,7 +26,11 @@ namespace tflite {
 
 uint32_t MicroProfiler::BeginEvent(const char* tag) {
   if (num_events_ == kMaxEvents) {
-    num_events_ = 0;
+    MicroPrintf(
+        "MicroProfiler errored out because total number of events exceeded the "
+        "maximum of %d.",
+        kMaxEvents);
+    TFLITE_ASSERT_FALSE;
   }
 
   tags_[num_events_] = tag;

tensorflow/lite/micro/micro_profiler.h

@@ -69,7 +69,7 @@ class MicroProfiler : public MicroProfilerInterface {
   // Maximum number of events that this class can keep track of. If we call
   // AddEvent more than kMaxEvents number of times, then the oldest event's
   // profiling information will be overwritten.
-  static constexpr int kMaxEvents = 1024;
+  static constexpr int kMaxEvents = 4096;
 
   const char* tags_[kMaxEvents];
   uint32_t start_ticks_[kMaxEvents];