[PATCH v4 3/3] cpuacct: Introduce cpuacct.usage_all to show all cpu stats together

[Zhao Lei]

In current code, we can get cpuacct data from several files,
but each file have its limit.

For example:
we can get cpu usage in user and kernel mode by cpuacct.stat,
but we can't get detail data of each cpu in above file.
we can get each cpu's kernel mode usage in cpuacct.usage_percpu_sys,
but we can't get user mode data in the same time.

This patch introduce cpuacct.usage_all, to show all detailed
cpu accounting data altogether:
 # cat cpuacct.usage_all
 cpu user system
 0 3809760299 5807968992
 1 3250329855 454612211
 ..

Any aspects of statistics data can be get from this file
with a simple data-processing code.

Signed-off-by: Zhao Lei <zhaolei@xxxxxxxxxxxxxx>
---
 kernel/sched/cpuacct.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c
index 677cd1a..bc0b309c 100644
--- a/kernel/sched/cpuacct.c
+++ b/kernel/sched/cpuacct.c
@@ -240,6 +240,42 @@ static int cpuacct_percpu_seq_show(struct seq_file *m, void *V)
 	return __cpuacct_percpu_seq_show(m, CPUACCT_STAT_NSTATS);
 }
 
+static int cpuacct_all_seq_show(struct seq_file *m, void *V)
+{
+	struct cpuacct *ca = css_ca(seq_css(m));
+	int index;
+	int cpu;
+
+	seq_puts(m, "cpu");
+	for (index = 0; index < CPUACCT_STAT_NSTATS; index++)
+		seq_printf(m, " %s", cpuacct_stat_desc[index]);
+	seq_puts(m, "\n");
+
+	for_each_possible_cpu(cpu) {
+		struct cpuacct_usage *cpuusage = per_cpu_ptr(ca->cpuusage, cpu);
+
+		seq_printf(m, "%d", cpu);
+
+		for (index = 0; index < CPUACCT_STAT_NSTATS; index++) {
+#ifndef CONFIG_64BIT
+			/*
+			 * Take rq->lock to make 64-bit read safe on 32-bit
+			 * platforms.
+			 */
+			raw_spin_lock_irq(&cpu_rq(cpu)->lock);
+#endif
+
+			seq_printf(m, " %llu", cpuusage->usages[index]);
+
+#ifndef CONFIG_64BIT
+			raw_spin_unlock_irq(&cpu_rq(cpu)->lock);
+#endif
+		}
+		seq_puts(m, "\n");
+	}
+	return 0;
+}
+
 static int cpuacct_stats_show(struct seq_file *sf, void *v)
 {
 	struct cpuacct *ca = css_ca(seq_css(sf));
@@ -294,6 +330,10 @@ static struct cftype files[] = {
 		.seq_show = cpuacct_percpu_sys_seq_show,
 	},
 	{
+		.name = "usage_all",
+		.seq_show = cpuacct_all_seq_show,
+	},
+	{
 		.name = "stat",
 		.seq_show = cpuacct_stats_show,
 	},
-- 
1.8.5.1