Messages in this thread | | | From | "Rafael J. Wysocki" <> | Date | Fri, 8 Nov 2019 10:45:03 +0100 | Subject | Re: [PATCH v2] cpuidle: Use nanoseconds as the unit of time |
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On Fri, Nov 8, 2019 at 9:45 AM Doug Smythies <dsmythies@telus.net> wrote: > > On 2019.11.07 17:44 Rafael J. Wysocki wrote: > > On Thu, Nov 7, 2019 at 3:25 PM Rafael J. Wysocki <rjw@rjwysocki.net> wrote: > >> > >> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > >> > >> Currently, the cpuidle subsystem uses microseconds as the unit of > >> time which (among other things) causes the idle loop to incur some > >> integer division overhead for no clear benefit. > >> > >> In order to allow cpuidle to measure time in nanoseconds, add two > >> additional fields, exit_latency_ns and target_residency_ns, to > >> represent the exit latency and target residency of an idle state > >> in nanoseconds, respectively, to struct cpuidle_state_usage and > >> initialize them with the help of the corresponding values in > >> microseconds provided by drivers. In addition to that, change > >> cpuidle_governor_latency_req() to return the idle state exit > >> latency constraint in nanoseconds. > >> > >> With that, meeasure idle state residency (last_residency_ns in > >> struct cpuidle_device and time_ns in struct cpuidle_driver) in > >> nanoseconds and update the cpuidle core and governors accordingly. > >> > >> However, the menu governor still computes typical intervals in > >> microseconds to avoid integer overflows. > > > > Since this addresses all of the comments received by the RFC version > > that was posted over a month ago and I don't see any more issues with > > it, I'm tempted to simply queue it up for 5.5 unless somebody sees a > > good enough reason why that would be a bad idea. > > Could I please have another day or two?
Sure, it won't go straight into linux-next anyway. :-)
> I did try the RFC version, but not much as I went off on those > teo issues and backtracked pretty quickly. > > I have been running this v2 today, with both menu and teo > governors. Acquiring some baseline reference data to compare > to now. The menu governor response seems different (Supporting > information/graphs will come later).
That may be good or bad, depending in what way it is different. :-)
> teo just started. > > I lost a bunch of time due to being somewhat linux-next challenged.
No worries, please take your time!
I very much appreciate the testing work you are doing.
Cheers!
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