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.
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);
