Messages in this thread | | | Date | Mon, 3 Aug 2020 14:58:38 +0100 | From | Ionela Voinescu <> | Subject | Re: [PATCH v2 2/7] cpufreq: set invariance scale factor on transition end |
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Hi Viresh,
On Thursday 30 Jul 2020 at 09:43:34 (+0530), Viresh Kumar wrote: > On 22-07-20, 10:37, Ionela Voinescu wrote: > > While the move of the invariance setter calls (arch_set_freq_scale()) > > from cpufreq drivers to cpufreq core maintained the previous > > functionality for existing drivers that use target_index() and > > fast_switch() for frequency switching, it also gives the possibility > > of adding support for users of the target() callback, which is exploited > > here. > > > > To be noted that the target() callback has been flagged as deprecated > > since: > > > > commit 9c0ebcf78fde ("cpufreq: Implement light weight ->target_index() routine") > > > > It also doesn't have that many users: > > > > cpufreq-nforce2.c:371:2: .target = nforce2_target, > > cppc_cpufreq.c:416:2: .target = cppc_cpufreq_set_target, > > gx-suspmod.c:439:2: .target = cpufreq_gx_target, > > pcc-cpufreq.c:573:2: .target = pcc_cpufreq_target, > > > > Similarly to the path taken for target_index() calls in the cpufreq core > > during a frequency change, all of the drivers above will mark the end of a > > frequency change by a call to cpufreq_freq_transition_end(). > > > > Therefore, cpufreq_freq_transition_end() can be used as the location for > > the arch_set_freq_scale() call to potentially inform the scheduler of the > > frequency change. > > > > This change maintains the previous functionality for the drivers that > > implement the target_index() callback, while also adding support for the > > few drivers that implement the deprecated target() callback. > > > > Two notes are worthwhile here: > > - In __target_index(), cpufreq_freq_transition_end() is called only for > > drivers that have synchronous notifications enabled. There is only one > > driver that disables them, > > > > drivers/cpufreq/powernow-k8.c:1142: .flags = CPUFREQ_ASYNC_NOTIFICATION, > > > > which is deprecated. > > I don't think this is deprecated.
Sorry, possibly 'deprecated' is a strong word.
As far as I knew acpi_cpufreq was recommended more recently for K8/K10 CPUs so that's why I decided not to create a special case for it, also considering that it was not supporting cpufreq-based frequency invariance to begin with.
We could support this as well by having a call to arch_set_freq_scale() on the else path in __target_index(). But given that there was only this one user of CPUFREQ_ASYNC_NOTIFICATION, I thought I'd propose this simpler version first.
Let me know if my reasoning is wrong.
Thank you, Ionela.
> > -- > viresh
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