Messages in this thread | | | Date | Mon, 4 Feb 2013 17:50:57 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH 0/4] CPUFreq: Implement per policy instances of governors |
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On Mon, Feb 04, 2013 at 09:07:11PM +0530, Viresh Kumar wrote: > I don't have board right now to take the snapshot, but it would be > like: > > $ tree /sys/devices/system/cpu/cpu0/cpufreq/ > /sys/devices/system/cpu/cpu0/cpufreq/ > ├── affected_cpus > ├── bios_limit > ├── cpb > ├── cpuinfo_cur_freq > ├── cpuinfo_max_freq > ├── cpuinfo_min_freq > ├── cpuinfo_transition_latency > ├── related_cpus > ├── scaling_available_frequencies > ├── scaling_available_governors > ├── scaling_cur_freq > ├── scaling_driver > ├── scaling_governor > ├── scaling_max_freq > ├── scaling_min_freq > ├── scaling_setspeed > └── stats > ├── time_in_state > ├── total_trans > └── trans_table > └── ondemand > ├── sampling_rate > ├── up_threshold > └── ignore_nice
So this is adding the current governor as a per-cpu thing.
> > One thing I've come to realize with the current interface is that if > > you want to change stuff, you need to iterate over all cpus instead of > > writing to a system-wide node. > > Not really. Following is the way by which cpu/cpu*/cpufreq directories > are created:
That's not what I meant - I meant from userspace:
for $i in $(grep processor /proc/cpuinfo | awk '{ print $3 }'); do echo "performance" > /sys/devices/system/cpu/cpu$i/cpufreq/scaling_governor; done
Instead of
echo "performance" > /sys/devices/system/cpu/cpufreq/scaling_governor
which is hypothetical but sets it for the whole system without fuss.
[ … ]
> I want to control it over clock-domain, but can't get that in cpu/cpufreq/. > Policies don't have numbers assigned to them.
So, give them names.
> So, i am working on ARM's big.LITTLE system where we have two > clusters. One of A15s and other of A7s. Because of their different > power ratings or performance figures, we need to have separate set of > ondemand tunables for them. And hence this patch. Though this patch is > required for any multi-cluster system.
So you want this (values after "="):
cpu/cpufreq/ |-> policy0 |-> name = A15 |-> min_freq = ... |-> max_freq = ... |-> affected_cpus = 0,1,2,... |-> ondemand |-> sampling_rate |-> up_threshold |-> ignore_nice ... |-> policy1 |-> name = A7 |-> min_freq = ... |-> max_freq = ... |-> affected_cpus = n,n+1,n+2,... |-> performance |-> sampling_rate |-> up_threshold |-> ignore_nice ...
Other arches create other policies and that's it. If you need another policy added to the set, you simply add 'policyN++' and that's it.
I think this is cleaner but whatever - I don't care that much. My only strong concern is that this thing should be a Kconfig option and optional for arches where it doesn't apply.
Thanks.
-- Regards/Gruss, Boris.
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