On 05/05/2015 02:11 PM, Preeti U Murthy wrote:

On 05/05/2015 12:03 PM, Shilpasri G Bhat wrote:

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Hi Preeti,

On 05/05/2015 09:30 AM, Preeti U Murthy wrote:

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Hi Shilpa,

On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote:

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Re-evaluate the chip's throttled state on recieving OCC_THROTTLE
notification by executing *throttle_check() on any one of the cpu on
the chip. This is a sanity check to verify if we were indeed
throttled/unthrottled after receiving OCC_THROTTLE notification.

We cannot call *throttle_check() directly from the notification
handler because we could be handling chip1's notification in chip2. So
initiate an smp_call to execute *throttle_check(). We are irq-disabled
in the notification handler, so use a worker thread to smp_call
throttle_check() on any of the cpu in the chipmask.

I see that the first patch takes care of reporting *per-chip* throttling
for pmax capping condition. But where are we taking care of reporting
"pstate set to safe" and "freq control disabled" scenarios per-chip ?

IMO let us not have "psafe" and "freq control disabled" states managed per-chip.
Because when the above two conditions occur it is likely to happen across all
chips during an OCC reset cycle. So I am setting 'throttled' to false on
OCC_ACTIVE and re-verifying if it actually is the case by invoking
*throttle_check().

Alright like I pointed in the previous reply, a comment to indicate that
psafe and freq control disabled conditions will fail when occ is
inactive and that all chips face the consequence of this will help.

From your explanation on the thread of the first patch of this series,

this will not be required.

So,
Reviewed-by: Preeti U Murthy <redacted>

Regards
Preeti U Murthy

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Signed-off-by: Shilpasri G Bhat <redacted>
---
 drivers/cpufreq/powernv-cpufreq.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
index 9268424..9618813 100644
--- a/drivers/cpufreq/powernv-cpufreq.c
+++ b/drivers/cpufreq/powernv-cpufreq.c

@@ -50,6 +50,8 @@ static bool rebooting, throttled, occ_reset;
 static struct chip {
 	unsigned int id;
 	bool throttled;
+	cpumask_t mask;
+	struct work_struct throttle;
 } *chips;

 static int nr_chips;

@@ -310,8 +312,9 @@ static inline unsigned int get_nominal_index(void)
 	return powernv_pstate_info.max - powernv_pstate_info.nominal;
 }

-static void powernv_cpufreq_throttle_check(unsigned int cpu)
+static void powernv_cpufreq_throttle_check(void *data)
 {
+	unsigned int cpu = smp_processor_id();
 	unsigned long pmsr;
 	int pmsr_pmax, pmsr_lp, i;

@@ -373,7 +376,7 @@ static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
 		return 0;

 	if (!throttled)
-		powernv_cpufreq_throttle_check(smp_processor_id());
+		powernv_cpufreq_throttle_check(NULL);

 	freq_data.pstate_id = powernv_freqs[new_index].driver_data;

@@ -418,6 +421,14 @@ static struct notifier_block powernv_cpufreq_reboot_nb = {
 	.notifier_call = powernv_cpufreq_reboot_notifier,
 };

+void powernv_cpufreq_work_fn(struct work_struct *work)
+{
+	struct chip *chip = container_of(work, struct chip, throttle);
+
+	smp_call_function_any(&chip->mask,
+			      powernv_cpufreq_throttle_check, NULL, 0);
+}
+
 static char throttle_reason[][30] = {
 					"No throttling",
 					"Power Cap",

@@ -433,6 +444,7 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 	struct opal_msg *occ_msg = msg;
 	uint64_t token;
 	uint64_t chip_id, reason;
+	int i;

 	if (msg_type != OPAL_MSG_OCC)
 		return 0;

@@ -466,6 +478,10 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 			occ_reset = false;
 			throttled = false;
 			pr_info("OCC: Active\n");
+
+			for (i = 0; i < nr_chips; i++)
+				schedule_work(&chips[i].throttle);
+
 			return 0;
 		}

@@ -476,6 +492,12 @@ static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
 		else if (!reason)
 			pr_info("OCC: Chip %u %s\n", (unsigned int)chip_id,
 				throttle_reason[reason]);
+		else
+			return 0;

Why the else section ? The code can never reach here, can it ?

When reason > 5 , we dont want to handle it.

Of course! My bad!

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+
+		for (i = 0; i < nr_chips; i++)
+			if (chips[i].id == chip_id)
+				schedule_work(&chips[i].throttle);
 	}

Should we not do this only when we get unthrottled so as to cross verify
if it is indeed the case ? In case of throttling notification, opal's
verdict is final and there is no need to cross verify right ?

Two reasons for invoking *throttle_check() on throttling:
1) We just got to know the reason and not the Pmax value we are getting
throttled to.
2) It could be a spurious message caused due to late/lost delivery. My point
here is let us not completely rely on the notification to declare throttling
unless we verify it from reading PMSR.

Sounds good.

Regards
Preeti U Murthy

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