proc: export statistics for softirq to /proc

Export statistics for softirq in /proc/softirqs and /proc/stat.

1. /proc/softirqs
Implement /proc/softirqs which shows the number of softirq
for each CPU like /proc/interrupts.

2. /proc/stat
Add the "softirq" line to /proc/stat.
This line shows the number of softirq for all cpu.
The first column is the total of all softirqs and
each subsequent column is the total for particular softirq.

[kosaki.motohiro@jp.fujitsu.com: remove redundant for_each_possible_cpu() loop]
Signed-off-by: Keika Kobayashi <kobayashi.kk@ncos.nec.co.jp>
Reviewed-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 60 insertions, 0 deletions

diff --git a/fs/proc/Makefile b/fs/proc/Makefile
index 63d965193b22..11a7b5c68153 100644
--- a/fs/proc/Makefile
+++ b/fs/proc/Makefile
@@ -18,6 +18,7 @@ proc-y	+= meminfo.o
 proc-y  += stat.o
 proc-y  += uptime.o
 proc-y  += version.o
+proc-y  += softirqs.o
 proc-$(CONFIG_PROC_SYSCTL)      += proc_sysctl.o
 proc-$(CONFIG_NET)              += proc_net.o
 proc-$(CONFIG_PROC_KCORE)       += kcore.o
diff --git a/fs/proc/softirqs.c b/fs/proc/softirqs.c
new file mode 100644
index 000000000000..1807c2419f17
--- /dev/null
+++ b/fs/proc/softirqs.c
@@ -0,0 +1,44 @@
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+/*
+ * /proc/softirqs  ... display the number of softirqs
+ */
+static int show_softirqs(struct seq_file *p, void *v)
+{
+        int i, j;
+
+        seq_printf(p, "                ");
+        for_each_possible_cpu(i)
+                seq_printf(p, "CPU%-8d", i);
+        seq_printf(p, "\n");
+
+        for (i = 0; i < NR_SOFTIRQS; i++) {
+                seq_printf(p, "%8s:", softirq_to_name[i]);
+                for_each_possible_cpu(j)
+                        seq_printf(p, " %10u", kstat_softirqs_cpu(i, j));
+                seq_printf(p, "\n");
+        }
+        return 0;
+}
+
+static int softirqs_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, show_softirqs, NULL);
+}
+
+static const struct file_operations proc_softirqs_operations = {
+        .open           = softirqs_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+static int __init proc_softirqs_init(void)
+{
+        proc_create("softirqs", 0, NULL, &proc_softirqs_operations);
+        return 0;
+}
+module_init(proc_softirqs_init);
diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 81e4eb60972e..7cc726c6d70a 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -29,6 +29,8 @@ static int show_stat(struct seq_file *p, void *v)
         cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
         cputime64_t guest;
         u64 sum = 0;
+        u64 sum_softirq = 0;
+        unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
         struct timespec boottime;
         unsigned int per_irq_sum;
 
@@ -53,6 +55,13 @@ static int show_stat(struct seq_file *p, void *v)
                         sum += kstat_irqs_cpu(j, i);
                 }
                 sum += arch_irq_stat_cpu(i);
+
+                for (j = 0; j < NR_SOFTIRQS; j++) {
+                        unsigned int softirq_stat = kstat_softirqs_cpu(j, i);
+
+                        per_softirq_sums[j] += softirq_stat;
+                        sum_softirq += softirq_stat;
+                }
         }
         sum += arch_irq_stat();
 
@@ -115,6 +124,12 @@ static int show_stat(struct seq_file *p, void *v)
                 nr_running(),
                 nr_iowait());
 
+        seq_printf(p, "softirq %llu", (unsigned long long)sum_softirq);
+
+        for (i = 0; i < NR_SOFTIRQS; i++)
+                seq_printf(p, " %u", per_softirq_sums[i]);
+        seq_printf(p, "\n");
+
         return 0;
 }