On Fri, Mar 18, 2016 at 5:11 AM, Michael Neuling <mi...@neuling.org> wrote:
> On Fri, 2016-03-18 at 15:04 +1100, Michael Neuling wrote:
>
>> On Wed, 2016-02-03 at 01:11 +0530, Shilpasri G Bhat wrote:
>>
>
>> > cpu_to_chip_id() does a DT walk through to find out the chip id by
>> > taking a contended device tree lock. This adds an unnecessary
>> > overhead
>> > in a hot path. So instead of calling cpu_to_chip_id() everytime
>> > cache
>> > the chip ids for all cores in the array 'core_to_chip_map' and use
>> > it
>> > in the hotpath.
>> >
>> > Reported-by: Anton Blanchard <an...@samba.org>
>> > Signed-off-by: Shilpasri G Bhat <shilpa.b...@linux.vnet.ibm.com>
>> > Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
>> > Acked-by: Viresh Kumar <viresh.ku...@linaro.org>
>> > ---
>> > No changes from v7.
>>
>> How about this instead? It removes the linear lookup and seems a lot
>> less complex.
This has gone in already. Can you please send a patch on top of it?
> BTW we never init nr_chips before using it. We also need something
> like.
>
> diff --git a/drivers/cpufreq/powernv-cpufreq.c
> b/drivers/cpufreq/powernv-cpufreq.c
> index d63d2cb..c819ed4 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -556,6 +556,8 @@ static int init_chip_info(void)
> unsigned int cpu, i;
> unsigned int prev_chip_id = UINT_MAX;
>
> + nr_chips = 0;
> +
> for_each_possible_cpu(cpu) {
> unsigned int id = cpu_to_chip_id(cpu);
>
>
Including this part too maybe?
Thanks,
Rafael
_______________________________________________
Linuxppc-dev mailing list
Linuxppc-dev@lists.ozlabs.org
https://lists.ozlabs.org/listinfo/linuxppc-dev
