On 1/10/24 13:56, Lukasz Luba wrote:
Hi Sibi,
Hey Lukasz,
Thanks for taking time to review the series!
+ Morten and Dietmar on CC
On 1/8/24 14:01, Sibi Sankar wrote:
Register for limit change notifications if supported with the help of
perf_notify_support interface and determine the throttled frequency
using the perf_opp_xlate to apply HW pressure.
Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
---
drivers/cpufreq/scmi-cpufreq.c | 42 +++++++++++++++++++++++++++++++++-
1 file changed, 41 insertions(+), 1 deletion(-)
diff --git a/drivers/cpufreq/scmi-cpufreq.c
b/drivers/cpufreq/scmi-cpufreq.c
index 4ee23f4ebf4a..53bc8868455d 100644
--- a/drivers/cpufreq/scmi-cpufreq.c
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -25,9 +25,13 @@ struct scmi_data {
int domain_id;
int nr_opp;
struct device *cpu_dev;
+ struct cpufreq_policy *policy;
cpumask_var_t opp_shared_cpus;
+ struct notifier_block limit_notify_nb;
};
+const struct scmi_handle *handle;
+static struct scmi_device *scmi_dev;
static struct scmi_protocol_handle *ph;
static const struct scmi_perf_proto_ops *perf_ops;
@@ -144,6 +148,22 @@ scmi_get_cpu_power(struct device *cpu_dev,
unsigned long *power,
return 0;
}
+static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned
long event, void *data)
+{
+ unsigned long freq_hz;
+ struct scmi_perf_limits_report *limit_notify = data;
+ struct scmi_data *priv = container_of(nb, struct scmi_data,
limit_notify_nb);
+ struct cpufreq_policy *policy = priv->policy;
+
+ if (perf_ops->perf_opp_xlate(ph, priv->domain_id,
limit_notify->range_max, &freq_hz))
+ return NOTIFY_OK;
+
+ /* Update HW pressure (the boost frequencies are accepted) */
+ arch_update_hw_pressure(policy->related_cpus, (freq_hz /
HZ_PER_KHZ));
This is wrong. The whole idea of the new HW pressure was that I wanted
to get rid of the 'signal smoothing' mechanism in order to get
instantaneous value from FW to task scheduler. Vincent created
2 interfaces in that new HW pressure:
1. cpufreq_update_pressure(policy) - raw variable
2. arch_update_hw_pressure(policy->related_cpus, (freq_hz / HZ_PER_KHZ))
- smoothing PELT mechanism, good for raw IRQ in drivers
In our SCMI cpufreq driver we need the 1st one:
cpufreq_update_pressure(policy)
The FW will do the 'signal smoothing or filtering' and won't
flood the kernel with hundreds of notifications.
Ack, even though I see no mention of filtering being mandated in the
SCMI specification, the scmi notification by itself will serve as a
rate limiter I guess.
So, please change that bit and add me, Morten and Dietmar on CC.
I would like to review it.
ack
-Sibi
Regards,
Lukasz
