Messages in this thread | | | Subject | Re: [PATCH] ARM: cpuidle: Support asymmetric idle definition | From | Sudeep Holla <> | Date | Mon, 22 May 2017 14:59:14 +0100 |
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On 22/05/17 14:34, Leo Yan wrote: > Hi Sudeep, > > On Mon, May 22, 2017 at 02:02:12PM +0100, Sudeep Holla wrote: > > [...] > >>>>>> On 19/05/17 17:45, Daniel Lezcano wrote: >>>>>>> Some hardware have clusters with different idle states. The current code does >>>>>>> not support this and fails as it expects all the idle states to be identical. >>>>>>> >>>>>>> Because of this, the Mediatek mtk8173 had to create the same idle state for a >>>>>>> big.Little system and now the Hisilicon 960 is facing the same situation. >>>>>>> >>>>>> >>>>>> While I agree the we don't support them today, it's better to benchmark >>>>>> and record/compare the gain we get with the support for cluster based >>>>>> idle states. >>>>> >>>>> Sorry, I don't get what you are talking about. What do you want to >>>>> benchmark ? Cluster idling ? >>>>> >>>> >>>> OK, I was not so clear. I had a brief chat with Lorenzo, we have few >>>> reason to have this support: >>>> 1. Different number of states between clusters >>>> 2. Different latencies(this is the one I was referring above, generally >>>> we keep worst case timings here and wanted to see if any platform >>>> measured improvements with different latencies in the idle states) >>> >>> I don't see the point. Are you putting into question the big little design? >>> >> >> Not exactly. Since they are generally worst case number, I wanted to >> check if someone saw real benefit with 2 different set of values. >> Anyways that's not important or blocking, just raised a point, so that >> we can stick some benchmarking results with this. > > In case you are interesting for Hikey960 idle states, you could see > the two clustsers have different idle states: > http://termbin.com/d7ed
Probably this if off-topic, but I found CPU_NAP_0 really interesting:
1. CPU_NAP_0 has arm,psci-suspend-param as 0x00000000 which generally not recommended to avoid conflict with WFI
2. Initially I assumed, CPU_NAP_0 is retention/standby state, but then I see "local-timer-stop", which indicates it's power down state which means arm,psci-suspend-param is wrong.
-- Regards, Sudeep
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