sched: latencytop support

LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.

Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 78 insertions, 0 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7411bfb0b7cc..91fa8e6ce8ad 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -310,6 +310,77 @@ static int proc_pid_schedstat(struct task_struct *task, char *buffer)
 }
 #endif
 
+#ifdef CONFIG_LATENCYTOP
+static int lstats_show_proc(struct seq_file *m, void *v)
+{
+        int i;
+        struct task_struct *task = m->private;
+        seq_puts(m, "Latency Top version : v0.1\n");
+
+        for (i = 0; i < 32; i++) {
+                if (task->latency_record[i].backtrace[0]) {
+                        int q;
+                        seq_printf(m, "%i %li %li ",
+                                task->latency_record[i].count,
+                                task->latency_record[i].time,
+                                task->latency_record[i].max);
+                        for (q = 0; q < LT_BACKTRACEDEPTH; q++) {
+                                char sym[KSYM_NAME_LEN];
+                                char *c;
+                                if (!task->latency_record[i].backtrace[q])
+                                        break;
+                                if (task->latency_record[i].backtrace[q] == ULONG_MAX)
+                                        break;
+                                sprint_symbol(sym, task->latency_record[i].backtrace[q]);
+                                c = strchr(sym, '+');
+                                if (c)
+                                        *c = 0;
+                                seq_printf(m, "%s ", sym);
+                        }
+                        seq_printf(m, "\n");
+                }
+
+        }
+        return 0;
+}
+
+static int lstats_open(struct inode *inode, struct file *file)
+{
+        int ret;
+        struct seq_file *m;
+        struct task_struct *task = get_proc_task(inode);
+
+        ret = single_open(file, lstats_show_proc, NULL);
+        if (!ret) {
+                m = file->private_data;
+                m->private = task;
+        }
+        return ret;
+}
+
+static ssize_t lstats_write(struct file *file, const char __user *buf,
+                            size_t count, loff_t *offs)
+{
+        struct seq_file *m;
+        struct task_struct *task;
+
+        m = file->private_data;
+        task = m->private;
+        clear_all_latency_tracing(task);
+
+        return count;
+}
+
+static const struct file_operations proc_lstats_operations = {
+        .open           = lstats_open,
+        .read           = seq_read,
+        .write          = lstats_write,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+};
+
+#endif
+
 /* The badness from the OOM killer */
 unsigned long badness(struct task_struct *p, unsigned long uptime);
 static int proc_oom_score(struct task_struct *task, char *buffer)
@@ -1020,6 +1091,7 @@ static const struct file_operations proc_fault_inject_operations = {
 };
 #endif
 
+
 #ifdef CONFIG_SCHED_DEBUG
 /*
  * Print out various scheduling related per-task fields:
@@ -2230,6 +2302,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
         INF("schedstat",  S_IRUGO, pid_schedstat),
 #endif
+#ifdef CONFIG_LATENCYTOP
+        REG("latency",  S_IRUGO, lstats),
+#endif
 #ifdef CONFIG_PROC_PID_CPUSET
         REG("cpuset",     S_IRUGO, cpuset),
 #endif
@@ -2555,6 +2630,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
         INF("schedstat", S_IRUGO, pid_schedstat),
 #endif
+#ifdef CONFIG_LATENCYTOP
+        REG("latency",  S_IRUGO, lstats),
+#endif
 #ifdef CONFIG_PROC_PID_CPUSET
         REG("cpuset",    S_IRUGO, cpuset),
 #endif