[PATCH] OProfile: add a useful statistic

Add a stat counting the (relatively common) case where a PC value is logged
but there is no (longer) any executable mapping covering that address.

drivers/oprofile/buffer_sync.c

@@ -308,8 +308,10 @@ static void add_us_sample(struct mm_struct * mm, struct op_sample * s)
  
  	cookie = lookup_dcookie(mm, s->eip, &offset);
  
-	if (!cookie)
+	if (!cookie) {
+		atomic_inc(&oprofile_stats.sample_lost_no_mapping);
 		return;
+	}
 
 	if (cookie != last_cookie) {
 		add_cookie_switch(cookie);

drivers/oprofile/oprofile_stats.c

@@ -32,6 +32,7 @@ void oprofile_reset_stats(void)
 	}
  
 	atomic_set(&oprofile_stats.sample_lost_no_mm, 0);
+	atomic_set(&oprofile_stats.sample_lost_no_mapping, 0);
 	atomic_set(&oprofile_stats.event_lost_overflow, 0);
 }
 
@@ -70,6 +71,8 @@ void oprofile_create_stats_files(struct super_block * sb, struct dentry * root)
  
 	oprofilefs_create_ro_atomic(sb, dir, "sample_lost_no_mm",
 		&oprofile_stats.sample_lost_no_mm);
+	oprofilefs_create_ro_atomic(sb, dir, "sample_lost_no_mapping",
+		&oprofile_stats.sample_lost_no_mapping);
 	oprofilefs_create_ro_atomic(sb, dir, "event_lost_overflow",
 		&oprofile_stats.event_lost_overflow);
 }

drivers/oprofile/oprofile_stats.h

@@ -14,6 +14,7 @@
  
 struct oprofile_stat_struct {
 	atomic_t sample_lost_no_mm;
+	atomic_t sample_lost_no_mapping;
 	atomic_t event_lost_overflow;
 };