Messages in this thread | | | From | "Doug Smythies" <> | Subject | RE: [RFT][PATCH v7 5/8] cpuidle: Return nohz hint from cpuidle_select() | Date | Thu, 22 Mar 2018 08:41:54 -0700 |
| |
On 2018.03.21 23:25 Doug Smythies wrote: > On 2018.03.21 15:15 Rafael J. Wysocki wrote: >> On Wed, Mar 21, 2018 at 6:59 PM, Thomas Ilsche wrote: >>> On 2018-03-21 15:36, Rafael J. Wysocki wrote: >>>> >>>> So please disregard this one entirely and take the v7.2 replacement >>>> instead of it:https://patchwork.kernel.org/patch/10299429/ >>>> >>>> The current versions (including the above) is in the git branch at >>>> >>>> git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git \ >>>> idle-loop-v7.2 >>> >>> With v7.2 (tested on SKL-SP from git) I see similar behavior in idle >>> as with v5: several cores which just keep the sched tick enabled. >>> Worse yet, some go only in C1 (not even C1E!?) despite sleeping the >>> full sched tick. >>> The resulting power consumption is ~105 W instead of ~ 70 W. >>> >>> https://wwwpub.zih.tu-dresden.de/~tilsche/powernightmares/v7_2_skl_sp_idle.png >>> >>> I have briefly ran v7 and I believe it was also affected.
I am not seeing any issues at all with V7.
>> >> Then it looks like menu_select() stubbornly thinks that the idle >> duration will be within the tick boundary on those cores. >> >> That may be because the bumping up of the correction factor in >> menu_reflect() is too conservative or it may be necessary to do >> something radical to measured_us in menu_update() in case of a tick >> wakeup combined with a large next_timer_us value. >> >> For starters, please see if the attached patch (on top of the >> idle-loop-v7.2 git branch) changes this behavior in any way. > > O.K. I am seeing some weirdness. > On my system with both V7.2 and V7.2 plus this patch, I observe > A spike in Idle State 1 residency every 34+ minutes. And slightly > higher average idle power than before. > (I might not have done V7 idle tests long enough).
I re-did the idle test on V7, and for longer. It is great. See line added to the idle graph for V7.2+:
http://fast.smythies.com/rjw_v72p_v7_idle.png
> > It can be seen in the frequency sweep I did earlier today, with V7.2: > > http://fast.smythies.com/rjw_freq_sweep_72_combined.png > > Despite the note on the graph that says it might be real, I don't think > it is (I forgot to delete the note). > > With V7.2+ sometimes the event occurs at 17 minute intervals. > Here is a idle graph (for reference: we have seen idle package power > pretty steady at ~3.7 watts before).
Now shown on the new graph. Link above.
> > http://fast.smythies.com/rjw_v72p_idle.png
... Doug
| |