On 30/10/2018 09:58, Viresh Kumar wrote:
> s/dmpis/dmips/ in $subject
>
> On 29-10-18, 17:23, Daniel Lezcano wrote:
>> In the case of assymetric SoC with the same micro-architecture, we
>
> asymmetric ?
>
>> have a group of CPUs with smaller OPPs than the other group. One
>> example is the 96boards dragonboard 820c. There is no dmips/MHz
>> difference between both groups, so no need to specify the values in
>> the DT. Unfortunately, without these defined, there is no scaling
>> capacity comutation triggered, so we need to write
>
> computation
>
>> 'capacity-dmips-mhz' for each CPU with the same value in order to
>> force the scaled capacity computation.
>>
>> Fix this by setting a default capacity to SCHED_CAPACITY_SCALE, if no
>> 'capacity-dmips-mhz' is defined in the DT.
>>
>> This was tested on db820c:
>> - specified values in the DT (correct results)
>> - partial values defined in the DT (error + fallback to defaults)
>> - no specified values in the DT (correct results)
>>
>> correct results are:
>> cat /sys/devices/system/cpu/cpu*/cpu_capacity
>> 758
>> 758
>> 1024
>> 1024
>>
>> ... respectively for CPU0, CPU1, CPU2 and CPU3.
>>
>> That reflects the capacity for the max frequencies 1593600 and 2150400.
>>
>> Cc: Chris Redpath <chris.redp...@linaro.org>
>> Cc: Quentin Perret <quentin.per...@linaro.org>
>> Cc: Viresh Kumar <viresh.ku...@linaro.org>
>> Cc: Amit Kucheria <amit.kuche...@linaro.org>
>> Cc: Nicolas Dechesne <nicolas.deche...@linaro.org>
>> Cc: Niklas Cassel <niklas.cas...@linaro.org>
>> Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org>
>> ---
>> drivers/base/arch_topology.c | 27 ++++++++++++++++++++++++++-
>> 1 file changed, 26 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
>> index 7311641..7d594a6 100644
>> --- a/drivers/base/arch_topology.c
>> +++ b/drivers/base/arch_topology.c
>> @@ -205,6 +205,21 @@ static struct notifier_block init_cpu_capacity_notifier
>> = {
>> .notifier_call = init_cpu_capacity_callback,
>> };
>>
>> +static int topology_set_default_capacity(void)
>> +{
>> + int cpu;
>> +
>> + raw_capacity = kzalloc(num_possible_cpus() * sizeof(*raw_capacity),
>> + GFP_KERNEL);
>> + if (!raw_capacity)
>> + return -ENOMEM;
>> +
>> + for_each_possible_cpu(cpu)
>> + raw_capacity[cpu] = SCHED_CAPACITY_SCALE;
>
> This isn't actually required as the value of raw_capacity isn't used
> anymore after this point in code. Rather it is forcefully updated in
> init_cpu_capacity_callback():
>
> raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
> policy->cpuinfo.max_freq / 1000UL;
>
> Maybe it is better to allocate raw_capacity once at boot and use
> another global variable as flag (raw_capacity is used as a flag right
> now at many places).
Can we keep the proposed change as is to simply fix the default value?
I want to do a separate change with a raw_capacity rewrite and remove
the workqueue freeing it.
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