Messages in this thread | | | From | Doug Smythies <> | Date | Tue, 8 Aug 2023 15:40:17 -0700 | Subject | Re: [RFT][PATCH v2 0/3] cpuidle: teo: Do not check timers unconditionally every time |
| |
On Tue, Aug 8, 2023 at 9:43 AM Rafael J. Wysocki <rafael@kernel.org> wrote: > On Tue, Aug 8, 2023 at 5:22 PM Doug Smythies <dsmythies@telus.net> wrote: > > On 2023.08.03 14:33 Rafael wrote: > > > On Thu, Aug 3, 2023 at 11:12 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > > >> > > >> Hi Folks, > > >> > > >> This is the second iteration of: > > >> > > >> https://lore.kernel.org/linux-pm/4511619.LvFx2qVVIh@kreacher/ > > >> > > >> with an additional patch. > > >> > > >> There are some small modifications of patch [1/3] and the new > > >> patch causes governor statistics to play a role in deciding whether > > >> or not to stop the scheduler tick. > > >> > > >> Testing would be much appreciated! > > > > > > For convenience, this series is now available in the following git branch: > > > > > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \ > > > pm-cpuidle-teo > > > > Hi Rafael, > > > > Thank you for the git branch link. > > > > I did some testing:
... deleted ...
> > Test 2: 6 core ping pong sweep: > > > > Pass a token between 6 CPUs on 6 different cores. > > Do a variable amount of work at each stop. > > > > Purpose: To utilize the midrange idle states > > and observe the transitions from between use of > > idle states. > > > > Results: There is some instability in the results > > in the early stages. > > For unknown reasons, the rjw governor sometimes works > > slower and at lower power. The condition is not 100% > > repeatable. > > > > Overall teo completed the test fastest (54.9 minutes) > > Followed by menu (56.2 minutes), then rjw (56.7 minutes), > > then ladder (58.4 minutes). teo is faster throughout the > > latter stages of the test, but at the cost of more power. > > The differences seem to be in the transition from idle > > state 1 to idle state 2 usage.
the magnitude of the later stages differences are significant.
... deleted ...
> Thanks a lot for doing this work, much appreciated! > > > Conclusions: Overall, I am not seeing a compelling reason to > > proceed with this patch set. > > On the other hand, if there is a separate compelling reason to do > that, it doesn't appear to lead to a major regression.
Agreed.
Just for additional information, a 6 core dwell test was run. The test conditions were cherry picked for dramatic effect:
teo: average: 1162.13 uSec/loop ; Std dev: 0.38 ryw: average: 1266.45 uSec/loop ; Std dev: 6.53 ; +9%
teo: average: 29.98 watts rjw: average: 30.30 watts (the same within thermal experimental error)
Details (power and idle stats over the 45 minute test period): http://smythies.com/~doug/linux/idle/teo-util2/6-13568-147097/perf/
| |