[Devel] [PATCH RH8 4/8] ve/fs/proc: Make per-thread and per-process allocation latencies.

[Andrey Zhadchenko]

From: Andrey Ryabinin <aryabinin at virtuozzo.com>

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>
Reviewed-by: Kirill Tkhai <ktkhai at virtuozzo.com>

Cc: Pavel Borzenkov <Pavel.Borzenkov at acronis.com>

Rebase to vz8:
 - As signal_struct moved from sched.h to sched/signal.h so changes did

(cherry-picked from c4cb66d5e70636c2089feb602226292a2513622a)
Signed-off-by: Andrey Zhadchenko <andrey.zhadchenko at virtuozzo.com>
---
 fs/proc/base.c               | 76 ++++++++++++++++++++++++++++++--------------
 include/linux/sched/signal.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 c8dc2e9..96db35f 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -533,24 +533,23 @@ 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++)
@@ -559,17 +558,43 @@ 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
 
 static int proc_oom_score(struct seq_file *m, struct pid_namespace *ns,
@@ -3097,7 +3122,7 @@ static int proc_pid_patch_state(struct seq_file *m, struct pid_namespace *ns,
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
 #ifdef CONFIG_VE
-	REG("vz_latency", S_IRUGO, proc_vz_lat_operations),
+	ONE("vz_latency", S_IRUGO, proc_tgid_vz_lat),
 #endif
 };
 
@@ -3480,6 +3505,9 @@ static int proc_tid_comm_permission(struct inode *inode, int mask)
 #ifdef CONFIG_LIVEPATCH
 	ONE("patch_state",  S_IRUSR, proc_pid_patch_state),
 #endif
+#ifdef CONFIG_VE
+	ONE("vz_latency", S_IRUGO, proc_tid_vz_lat),
+#endif
 };
 
 static int proc_tid_base_readdir(struct file *file, struct dir_context *ctx)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 57cf2c5..adfe9cc 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -211,6 +211,9 @@ 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;
 	struct tty_audit_buf *tty_audit_buf;
diff --git a/kernel/exit.c b/kernel/exit.c
index 0922ca9..8fde663 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -723,6 +723,20 @@ 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 __noreturn do_exit(long code)
 {
 	struct task_struct *tsk = current;
@@ -791,6 +805,8 @@ void __noreturn do_exit(long code)
 #endif
 		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)
-- 
1.8.3.1