Messages in this thread | | | From | Todd Kjos <> | Date | Thu, 2 Jun 2022 12:02:53 -0700 | Subject | Re: [PATCH 3/3] thermal/sysfs: Remove cooling device sysfs statistics |
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On Thu, Jun 2, 2022 at 2:16 AM Lukasz Luba <lukasz.luba@arm.com> wrote: > > > > On 6/2/22 09:37, Daniel Lezcano wrote: > > > > Hi Lukasz, > > > > [Adding Todd] > > > > On 01/06/2022 17:33, Lukasz Luba wrote: > >> Hi Daniel, > >> > >> > >> On 6/1/22 16:14, Daniel Lezcano wrote: > >>> The statistics are for debugging purpose and belong to debugfs rather > >>> than sysfs. As the previous changes introduced the same statistics in > >>> debugfs, those in sysfs are no longer needed and can be removed. > >> > >> I just want to let you know that in current Android kernels we cannot > >> even compile the kernel with CONFIG_DEBUG_FS. > > > > Right, it makes sense. Precisely, with the sysfs stats they are always > > compiled in for the Android kernel and is a problem for low memory > > systems. While debugfs can fulfill its purpose in the developement and > > will be removed in production systems. > > True. > > > > >> I have this pain with > >> Energy Model there... Some vendors might see useful info via this > >> sysfs interface in bring-up of the SoC. > > > > Well alternatively, information can be extracted from procfs in the > > device-tree description. > > > > What prevents to add energy information in sysfs now that the energy > > model is per device ? > > Probably nothing, but we need strong need. I have proposed this > a few times internally, but this must have a requirement. > If a user-space tool would ask for it, then I could send a patch > exposing the sysfs. So far we have only one user-space tool, which > suffers the missing debugfs EM dir: LISA (but we are working on a > workaround for it). > If you have a tool or plan to have such, which uses EM, please let > me know. I'm gathering the requirements. > > > > >> I don't know if there are user-space tools tracking this > >> information via sysfs. We probably should check that. > >> > >> I agree that these statistics look more like debug info, rather than > >> something useful for control. > >> > >> Furthermore, we have trace events for the cooling state changes, which > >> should be good enough for bring-up and experiments. > >> > >> I don't have strong preferences here. I tend to agree to remove this > >> interface if there are no user-space tools using it. > > > > I agree userspace can also get information about the transition but the > > goal of the debugfs is also add information about thermal internals like > > average temperature at mitigation time, min and max, timings, etc ... > > > > > > I see, it makes sense. Let's see if Todd and Android folks don't > use this thermal sysfs stats, so we could remove them.
Android HALs do use the thermal sysfs stats. debugfs isn't a viable replacement since debugfs must not be mounted during normal operation.
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