Re: [PATCH 1/2] cpufreq: powernv: Adding fast_switch for schedutil

Thanks Viresh for taking a look at it.

I will make the mentioned changes in the next version of the patch.


Regards

Akshay Adiga


On 11/04/2016 12:03 PM, Viresh Kumar wrote:

On 04-11-16, 10:57, Akshay Adiga wrote:

quoted

Adding fast_switch which does light weight operation to
set the desired pstate.

Signed-off-by: Akshay Adiga <redacted>
---
  drivers/cpufreq/powernv-cpufreq.c | 22 +++++++++++++++++++++-
  1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index d3ffde8..09a0496 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -752,9 +752,12 @@ static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
  	spin_lock_init(&gpstates->gpstate_lock);
  	ret = cpufreq_table_validate_and_show(policy, powernv_freqs);
  
-	if (ret < 0)
+	if (ret < 0) {
  		kfree(policy->driver_data);
+		return ret;
+	}
  
+	policy->fast_switch_possible = true;
  	return ret;
  }
  

@@ -897,6 +900,22 @@ static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
  	del_timer_sync(&gpstates->timer);
  }
  
+static unsigned int powernv_fast_switch(struct cpufreq_policy *policy,
+					unsigned int target_freq)
+{
+	int index;
+	struct powernv_smp_call_data freq_data;
+
+	index = cpufreq_table_find_index_dl(policy, target_freq);
+	if (index < 0 || index >= powernv_pstate_info.nr_pstates)
+		return CPUFREQ_ENTRY_INVALID;

I don't think such a check is required at all. It wouldn't happen without a BUG
in kernel.

quoted

+	freq_data.pstate_id = powernv_freqs[index].driver_data;
+	freq_data.gpstate_id = powernv_freqs[index].driver_data;
+	set_pstate(&freq_data);
+
+	return powernv_freqs[index].frequency;
+}
+
  static struct cpufreq_driver powernv_cpufreq_driver = {
  	.name		= "powernv-cpufreq",
  	.flags		= CPUFREQ_CONST_LOOPS,

@@ -904,6 +923,7 @@ static struct cpufreq_driver powernv_cpufreq_driver = {
  	.exit		= powernv_cpufreq_cpu_exit,
  	.verify		= cpufreq_generic_frequency_table_verify,
  	.target_index	= powernv_cpufreq_target_index,
+	.fast_switch	= powernv_fast_switch,
  	.get		= powernv_cpufreq_get,
  	.stop_cpu	= powernv_cpufreq_stop_cpu,
  	.attr		= powernv_cpu_freq_attr,

-- 
2.7.4