[Devel] [PATCH rh7 v2 2/2] ve/fs/proc: Make per-thread and per-process allocation latencies.

[Andrey Ryabinin]

Follow-up for 6d9a9210395e ("ve/page_alloc, kstat: account allocation latencies per-task")
Make per-thread and per-process allocation latencies:

  - /proc/<pid>/vz_latency - cumulative for a thread group
  - /proc/<pid>/tasks/<pid>/vz_latency - thread-specific

During allocation we collect per-thread latency. When thread dies,
it submits its own latencies into shared task->signal.alloc_lat struct.
/proc/<pid>/vz_latency - sums allocation latencies over all live threads
plus latencies of already dead tasks from task->signal.alloc_lat.

https://jira.sw.ru/browse/PSBM-81395
Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Pavel Borzenkov <Pavel.Borzenkov at acronis.com>
---
Changes since v1:

 - Change hard-coded 3 to the ARRAY_SIZE(alloc_types)

 fs/proc/base.c        | 76 +++++++++++++++++++++++++++++++++++----------------
 include/linux/sched.h |  3 ++
 kernel/exit.c         | 16 +++++++++++
 3 files changed, 71 insertions(+), 24 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 5646a351c076..88d026098f31 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -583,24 +583,23 @@ static void lastlat_seq_show(struct seq_file *m,
 	seq_printf(m, "%-12s %20Lu %20lu\n", name,
 			snap->totlat, snap->count);
 }
+static const char *alloc_descr[] = {
+	"allocatomic:",
+	"alloc:",
+	"allocmp:",
+};
+static const int alloc_types[] = {
+	KSTAT_ALLOCSTAT_ATOMIC,
+	KSTAT_ALLOCSTAT_LOW,
+	KSTAT_ALLOCSTAT_LOW_MP,
+};
 
-static int vz_lat_show_proc(struct seq_file *m, void *v)
+static int proc_tid_vz_lat(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
 {
 	int i;
-	struct inode *inode = m->private;
-	struct task_struct *task = get_proc_task(inode);
-	static const char *alloc_descr[] = {
-		"allocatomic:",
-		"alloc:",
-		"allocmp:",
-	};
-	static const int alloc_types[] = {
-		KSTAT_ALLOCSTAT_ATOMIC,
-		KSTAT_ALLOCSTAT_LOW,
-		KSTAT_ALLOCSTAT_LOW_MP,
-	};
 
-	seq_printf(m, "%-11s %20s %20s\n",
+	seq_printf(m, "%-12s %20s %20s\n",
 			"Type", "Total_lat", "Calls");
 
 	for (i = 0; i < ARRAY_SIZE(alloc_types); i++)
@@ -609,17 +608,43 @@ static int vz_lat_show_proc(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int vz_lat_open(struct inode *inode, struct file *file)
+static int proc_tgid_vz_lat(struct seq_file *m, struct pid_namespace *ns,
+			struct pid *pid, struct task_struct *task)
 {
-	return single_open(file, vz_lat_show_proc, inode);
-}
+	int i;
+	unsigned long flags;
+	u64 lat[ARRAY_SIZE(alloc_types)];
+	u64 count[ARRAY_SIZE(alloc_types)];
 
-static const struct file_operations proc_vz_lat_operations = {
-	.open		= vz_lat_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
+	for (i = 0; i < ARRAY_SIZE(alloc_types); i++) {
+		lat[i] = task->alloc_lat[alloc_types[i]].totlat;
+		count[i] = task->alloc_lat[alloc_types[i]].count;
+	}
+
+	if (lock_task_sighand(task, &flags)) {
+		struct task_struct *t = task;
+		while_each_thread(task, t) {
+			for (i = 0; i < ARRAY_SIZE(alloc_types); i++) {
+				lat[i] += t->alloc_lat[alloc_types[i]].totlat;
+				count[i] += t->alloc_lat[alloc_types[i]].count;
+			}
+		}
+		for (i = 0; i < ARRAY_SIZE(alloc_types); i++) {
+			lat[i] += t->signal->alloc_lat[alloc_types[i]].totlat;
+			count[i] += t->signal->alloc_lat[alloc_types[i]].count;
+		}
+		unlock_task_sighand(task, &flags);
+	}
+
+	seq_printf(m, "%-12s %20s %20s\n",
+			"Type", "Total_lat", "Calls");
+
+	for (i = 0; i < ARRAY_SIZE(alloc_types); i++)
+		seq_printf(m, "%-12s %20Lu %20Lu\n", alloc_descr[i],
+			lat[i], count[i]);
+
+	return 0;
+}
 #endif
 
 #ifdef CONFIG_CGROUPS
@@ -3060,7 +3085,7 @@ static const struct pid_entry tgid_base_stuff[] = {
 	REG("aio",	  S_IRUGO|S_IWUSR, proc_aio_operations),
 #endif
 #ifdef CONFIG_VE
-	REG("vz_latency", S_IRUGO, proc_vz_lat_operations),
+	ONE("vz_latency", S_IRUGO, proc_tgid_vz_lat),
 #endif
 };
 
@@ -3410,6 +3435,9 @@ static const struct pid_entry tid_base_stuff[] = {
 	REG("projid_map", S_IRUGO|S_IWUSR, proc_projid_map_operations),
 	REG("setgroups",  S_IRUGO|S_IWUSR, proc_setgroups_operations),
 #endif
+#ifdef CONFIG_VE
+	ONE("vz_latency", S_IRUGO, proc_tid_vz_lat),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file * filp,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 1595be347b6d..9189d1b160c8 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -710,6 +710,9 @@ struct signal_struct {
 #ifdef CONFIG_TASKSTATS
 	struct taskstats *stats;
 #endif
+#ifdef CONFIG_VE
+	struct kstat_lat_snap_struct alloc_lat[KSTAT_ALLOCSTAT_NR];
+#endif
 #ifdef CONFIG_AUDIT
 	unsigned audit_tty;
 	unsigned audit_tty_log_passwd;
diff --git a/kernel/exit.c b/kernel/exit.c
index ce5d456b590b..1f243edca11a 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -736,6 +736,20 @@ static void check_stack_usage(void)
 static inline void check_stack_usage(void) {}
 #endif
 
+void kstat_add_dying(struct task_struct *tsk)
+{
+#ifdef CONFIG_VE
+	int i;
+
+	spin_lock_irq(&tsk->sighand->siglock);
+	for (i = 0; i < KSTAT_ALLOCSTAT_NR; i++) {
+		tsk->signal->alloc_lat[i].totlat += tsk->alloc_lat[i].totlat;
+		tsk->signal->alloc_lat[i].count += tsk->alloc_lat[i].count;
+	}
+	spin_unlock_irq(&tsk->sighand->siglock);
+#endif
+}
+
 void do_exit(long code)
 {
 	struct task_struct *tsk = current;
@@ -808,6 +822,8 @@ void do_exit(long code)
 		exit_itimers(tsk->signal);
 		if (tsk->mm)
 			setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
+	} else {
+		kstat_add_dying(tsk);
 	}
 	acct_collect(code, group_dead);
 	if (group_dead)
-- 
2.16.1