[telemetry] Fix CPU metric jiffie overflow correction.

tools/perf/metrics/cpu.py

Index: tools/perf/metrics/cpu.py
diff --git a/tools/perf/metrics/cpu.py b/tools/perf/metrics/cpu.py
index 0709783965d59acb5badafda51a3e278273cf595..8975853b664651bff87a895c0dc1b0f7f1f9b220 100644
--- a/tools/perf/metrics/cpu.py
+++ b/tools/perf/metrics/cpu.py
@@ -87,11 +87,11 @@ def _SubtractCpuStats(cpu_stats, start_cpu_stats):
                   start_cpu_stats[process_type]['TotalTime'])
     # Fix overflow for 32-bit jiffie counter, 64-bit counter will not overflow.
     # Linux kernel starts with a value close to an overflow, so correction is
-    # necessary.
+    # necessary. Assume jiffie counter is at 100 Hz.
     if total_time < 0:
-      total_time += 2 ** 32
+      total_time += 2 ** 32 / 100.
     # Assert that the arguments were given in the correct order.
-    assert total_time > 0 and total_time < 2 ** 31, (
+    assert total_time > 0 and total_time < 2 ** 31 / 100., (
         'Expected total_time > 0, was: %d' % total_time)
     cpu_usage[process_type] = float(cpu_process_time) / total_time
   return cpu_usage