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05 April 2024, 19:05:47 UTC
Revision d4794f25f122aa1a8a073be51112edaa723ffff4 authored by Yazen Ghannam on 25 March 2019, 17:32:42 UTC, committed by Len Brown on 31 August 2019, 18:48:34 UTC 
tools/power turbostat: Make interval calculation per thread to reduce jitter
 
Turbostat currently normalizes TSC and other values by dividing by an
interval. This interval is the delta between the start of one global
(all counters on all CPUs) sampling and the start of another. However,
this introduces a lot of jitter into the data.

In order to reduce jitter, the interval calculation should be based on
timestamps taken per thread and close to the start of the thread's
sampling.

Define a per thread time value to hold the delta between samples taken
on the thread.

Use the timestamp taken at the beginning of sampling to calculate the
delta.

Move the thread's beginning timestamp to after the CPU migration to
avoid jitter due to the migration.

Use the global time delta for the average time delta.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Len Brown <len.brown@intel.com>
1 parent d743dae
History
Tip revision: d4794f25f122aa1a8a073be51112edaa723ffff4 authored by Yazen Ghannam on 25 March 2019, 17:32:42 UTC
tools/power turbostat: Make interval calculation per thread to reduce jitter
Tip revision: d4794f2
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