[PATCH 3/7] cpufreq: intel_pstate: Add debugfs file stats

[Stratos Karafotis]

Add stats file in debugfs under driver's parent directory
(pstate_snb) which counts the time in nsecs per requested
P state and the number of times the specific state
was requested.

The file presents the statistics per logical CPU in the
following format. The time is displayed in msecs:

CPU0
P-state        Time     Count
     16     4882777     23632
     17       21210       174
     18      549781      3300
     19       51171       461
     20       35487       394
     21       18173       219
     22       13752       258
     23        6048       172
     24        7754       177
     25        4587       151
     26        5465       162
     27        1432        47
     28         863        54
     29        1448        50
     30        1030        47
     31        1472        62
     32        2221        68
     33        1869        60
     34        2140        70
     39       85446      3803

...

The file can be used for debugging but also for monitoring
various system workloads.

Also, make the debugfs_parent local as we never remove
the driver's debugfs files.

Signed-off-by: Stratos Karafotis <stratosk@xxxxxxxxxxxx>
---
 drivers/cpufreq/intel_pstate.c | 80 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 31e2ae5..3a49269 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -86,6 +86,12 @@ struct _pid {
 	int32_t last_err;
 };
 
+struct pstate_stat {
+	int pstate;
+	u64 time;
+	u64 count;
+};
+
 struct cpudata {
 	int cpu;
 
@@ -99,6 +105,7 @@ struct cpudata {
 	u64	prev_aperf;
 	u64	prev_mperf;
 	struct sample sample;
+	struct pstate_stat *stats;
 };
 
 static struct cpudata **all_cpu_data;
@@ -256,9 +263,59 @@ static struct pid_param pid_files[] = {
 	{NULL, NULL}
 };
 
-static struct dentry *debugfs_parent;
+static inline unsigned int stats_state_index(struct cpudata *cpu, int pstate)
+{
+	if (pstate <= cpu->pstate.max_pstate)
+		return pstate - cpu->pstate.min_pstate;
+	else
+		return cpu->pstate.max_pstate - cpu->pstate.min_pstate + 1;
+}
+
+static int stats_debug_show(struct seq_file *m, void *unused)
+{
+	struct cpudata *cpu;
+	int i, j, cnt;
+
+	get_online_cpus();
+	for_each_online_cpu(i) {
+		if (all_cpu_data[i])
+			cpu = all_cpu_data[i];
+		else
+			continue;
+
+		seq_printf(m, "CPU%u\n", i);
+		seq_puts(m, "P-state        Time     Count\n");
+
+		cnt = cpu->pstate.max_pstate - cpu->pstate.min_pstate + 2;
+		for (j = 0; j < cnt; j++)
+			seq_printf(m, "%7u %11llu %9llu\n",
+				   cpu->stats[j].pstate,
+				   cpu->stats[j].time / USEC_PER_MSEC,
+				   cpu->stats[j].count);
+
+		seq_puts(m, "\n");
+	}
+	put_online_cpus();
+
+	return 0;
+}
+
+static int stats_debug_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, stats_debug_show, inode->i_private);
+}
+
+static const struct file_operations fops_stats_pstate = {
+	.open		= stats_debug_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+	.owner		= THIS_MODULE,
+};
+
 static void intel_pstate_debug_expose_params(void)
 {
+	struct dentry *debugfs_parent;
 	int i = 0;
 
 	debugfs_parent = debugfs_create_dir("pstate_snb", NULL);
@@ -270,6 +327,8 @@ static void intel_pstate_debug_expose_params(void)
 				&fops_pid_param);
 		i++;
 	}
+	debugfs_create_file("stats", S_IRUSR | S_IRGRP, debugfs_parent, NULL,
+			    &fops_stats_pstate);
 }
 
 /************************** debugfs end ************************/
@@ -610,6 +669,7 @@ static inline void intel_pstate_calc_scaled_busy(struct cpudata *cpu)
 	int32_t core_busy, max_pstate, current_pstate, sample_ratio;
 	u32 duration_us;
 	u32 sample_time;
+	unsigned int i;
 
 	core_busy = cpu->sample.core_pct_busy;
 	max_pstate = int_tofp(cpu->pstate.max_pstate);
@@ -626,6 +686,10 @@ static inline void intel_pstate_calc_scaled_busy(struct cpudata *cpu)
 	}
 
 	cpu->sample.busy_scaled = core_busy;
+
+	i = stats_state_index(cpu, cpu->pstate.current_pstate);
+	cpu->stats[i].time += duration_us;
+	cpu->stats[i].count++;
 }
 
 static inline void intel_pstate_adjust_busy_pstate(struct cpudata *cpu)
@@ -692,6 +756,7 @@ MODULE_DEVICE_TABLE(x86cpu, intel_pstate_cpu_ids);
 static int intel_pstate_init_cpu(unsigned int cpunum)
 {
 	struct cpudata *cpu;
+	unsigned int i, cnt;
 
 	all_cpu_data[cpunum] = kzalloc(sizeof(struct cpudata), GFP_KERNEL);
 	if (!all_cpu_data[cpunum])
@@ -701,6 +766,17 @@ static int intel_pstate_init_cpu(unsigned int cpunum)
 
 	intel_pstate_get_cpu_pstates(cpu);
 
+	/* cnt equals to number of p-states + 1 (for turbo p-state) */
+	cnt = cpu->pstate.max_pstate - cpu->pstate.min_pstate + 2;
+	cpu->stats = kzalloc(sizeof(*cpu->stats) * cnt, GFP_KERNEL);
+	if (!cpu->stats) {
+		kfree(all_cpu_data[cpunum]);
+		return -ENOMEM;
+	}
+	for (i = 0; i < cnt - 1; i++)
+		cpu->stats[i].pstate = cpu->pstate.min_pstate + i;
+	cpu->stats[cnt - 1].pstate = cpu->pstate.turbo_pstate;
+
 	cpu->cpu = cpunum;
 
 	init_timer_deferrable(&cpu->timer);
@@ -779,6 +855,7 @@ static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
 
 	del_timer_sync(&all_cpu_data[cpu_num]->timer);
 	intel_pstate_set_pstate(cpu, cpu->pstate.min_pstate);
+	kfree(all_cpu_data[cpu_num]->stats);
 	kfree(all_cpu_data[cpu_num]);
 	all_cpu_data[cpu_num] = NULL;
 }
@@ -980,6 +1057,7 @@ out:
 	for_each_online_cpu(cpu) {
 		if (all_cpu_data[cpu]) {
 			del_timer_sync(&all_cpu_data[cpu]->timer);
+			kfree(all_cpu_data[cpu]->stats);
 			kfree(all_cpu_data[cpu]);
 		}
 	}
-- 
1.9.3
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