Messages in this thread | | | From | "Ghannam, Yazen" <> | Subject | RE: [PATCH] tools/power turbostat: Make interval calculation per thread to reduce jitter | Date | Tue, 23 Apr 2019 17:53:02 +0000 |
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> -----Original Message----- > From: linux-kernel-owner@vger.kernel.org <linux-kernel-owner@vger.kernel.org> On Behalf Of Ghannam, Yazen > Sent: Monday, March 25, 2019 12:33 PM > To: linux-pm@vger.kernel.org > Cc: Ghannam, Yazen <Yazen.Ghannam@amd.com>; linux-kernel@vger.kernel.org; lenb@kernel.org > Subject: [PATCH] tools/power turbostat: Make interval calculation per thread to reduce jitter > > From: Yazen Ghannam <yazen.ghannam@amd.com> > > 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> > ---
Hi Len,
Any comments on this patch?
Thanks, Yazen
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