readahead statistics slimmed down

Index: linux/mm/readahead.c
===================================================================
@@ -93,7 +93,6 @@ enum ra_event {
 	RA_EVENT_READAHEAD_MUTILATE,	/* read-ahead mutilated by imbalanced aging */
 	RA_EVENT_READAHEAD_RESCUE,	/* read-ahead rescued */
 
-	RA_EVENT_READAHEAD_CUBE,
 	RA_EVENT_COUNT
 };
 

@@ -1784,9 +1783,19 @@ void readahead_cache_hit(struct file_ra_
 #ifdef CONFIG_DEBUG_READAHEAD
 
 #include <linux/init.h>
-#include <linux/jiffies.h>
 #include <linux/debugfs.h>
-#include <linux/seq_file.h>
+#include <linux/statistic.h>
+
+#define RA_STAT_COUNT		(RA_EVENT_COUNT * RA_CLASS_COUNT)
+
+static struct statistic		ra_stat[RA_STAT_COUNT];
+static struct statistic_info	ra_stat_info[RA_STAT_COUNT];
+
+static struct statistic_interface ra_stat_if = {
+	.stat = ra_stat,
+	.info = ra_stat_info,
+	.number = RA_STAT_COUNT
+};
 
 static const char * const ra_class_name[] = {
 	"total",

@@ -1816,162 +1825,51 @@ static const char * const ra_event_name[
 	"readahead_rescue"
 };
 
-static unsigned long ra_events[RA_CLASS_COUNT][RA_EVENT_COUNT][2];
+#define RA_STAT_NAME_SIZE	32
+static char 			ra_stat_name[RA_STAT_COUNT][RA_STAT_NAME_SIZE];
+
+static struct statistic_info ra_stat_info_template = {
+	.x_unit	  = "pages",
+	.y_unit	  = "request",
+	.defaults = "type=counter",
+};
 
 static void ra_account(struct file_ra_state *ra, enum ra_event e, int pages)
 {
 	enum ra_class c;
 
-	if (!readahead_debug_level)
-		return;
-
 	if (pages < 0) {
 		pages = -pages;
 		c = ra_class_old(ra);
 	} else
 		c = ra_class_new(ra);
-
 	if (!c)
 		c = RA_CLASS_NONE;
 
-	ra_events[c][e][0] += 1;
-	ra_events[c][e][1] += pages;
-
-	if (e == RA_EVENT_READAHEAD)
-		ra_events[c][RA_EVENT_READAHEAD_CUBE][1] += pages * pages;
+	statistic_inc(ra_stat, e * RA_CLASS_COUNT + c, pages);
 }
 
-static int ra_events_show(struct seq_file *s, void *_)
-{
-	int i;
-	int c;
-	int e;
-	static const char event_fmt[] = "%-16s";
-	static const char class_fmt[] = "%10s";
-	static const char item_fmt[] = "%10lu";
-	static const char percent_format[] = "%9lu%%";
-	static const char * const table_name[] = {
-		"[table requests]",
-		"[table pages]",
-		"[table summary]"};
-
-	for (i = 0; i <= 1; i++) {
-		for (e = 0; e < RA_EVENT_COUNT; e++) {
-			ra_events[RA_CLASS_ALL][e][i] = 0;
-			for (c = RA_CLASS_INITIAL; c < RA_CLASS_NONE; c++)
-				ra_events[RA_CLASS_ALL][e][i] += ra_events[c][e][i];
-		}
-
-		seq_printf(s, event_fmt, table_name[i]);
-		for (c = 0; c < RA_CLASS_COUNT; c++)
-			seq_printf(s, class_fmt, ra_class_name[c]);
-		seq_puts(s, "\n");
-
-		for (e = 0; e < RA_EVENT_COUNT; e++) {
-			if (e == RA_EVENT_READAHEAD_CUBE)
-				continue;
-			if (e == RA_EVENT_READAHEAD_HIT && i == 0)
-				continue;
-			if (e == RA_EVENT_IO_BLOCK && i == 1)
-				continue;
-
-			seq_printf(s, event_fmt, ra_event_name[e]);
-			for (c = 0; c < RA_CLASS_COUNT; c++)
-				seq_printf(s, item_fmt, ra_events[c][e][i]);
-			seq_puts(s, "\n");
-		}
-		seq_puts(s, "\n");
-	}
-
-	seq_printf(s, event_fmt, table_name[2]);
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, class_fmt, ra_class_name[c]);
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "random_rate");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, percent_format,
-			(ra_events[c][RA_EVENT_RANDOM_READ][0] * 100) /
-			((ra_events[c][RA_EVENT_RANDOM_READ][0] +
-			  ra_events[c][RA_EVENT_READAHEAD][0]) | 1));
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "ra_hit_rate");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, percent_format,
-			(ra_events[c][RA_EVENT_READAHEAD_HIT][1] * 100) /
-			(ra_events[c][RA_EVENT_READAHEAD][1] | 1));
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "la_hit_rate");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, percent_format,
-			(ra_events[c][RA_EVENT_LOOKAHEAD_HIT][0] * 100) /
-			(ra_events[c][RA_EVENT_LOOKAHEAD][0] | 1));
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "var_ra_size");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, item_fmt,
-			(ra_events[c][RA_EVENT_READAHEAD_CUBE][1] -
-			 ra_events[c][RA_EVENT_READAHEAD][1] *
-			(ra_events[c][RA_EVENT_READAHEAD][1] /
-			(ra_events[c][RA_EVENT_READAHEAD][0] | 1))) /
-			(ra_events[c][RA_EVENT_READAHEAD][0] | 1));
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "avg_ra_size");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, item_fmt,
-			(ra_events[c][RA_EVENT_READAHEAD][1] +
-			 ra_events[c][RA_EVENT_READAHEAD][0] / 2) /
-			(ra_events[c][RA_EVENT_READAHEAD][0] | 1));
-	seq_puts(s, "\n");
-
-	seq_printf(s, event_fmt, "avg_la_size");
-	for (c = 0; c < RA_CLASS_COUNT; c++)
-		seq_printf(s, item_fmt,
-			(ra_events[c][RA_EVENT_LOOKAHEAD][1] +
-			 ra_events[c][RA_EVENT_LOOKAHEAD][0] / 2) /
-			(ra_events[c][RA_EVENT_LOOKAHEAD][0] | 1));
-	seq_puts(s, "\n");
-
-	return 0;
-}
-
-static int ra_events_open(struct inode *inode, struct file *file)
-{
-	return single_open(file, ra_events_show, NULL);
-}
-
-static ssize_t ra_events_write(struct file *file, const char __user *buf,
-						size_t size, loff_t *offset)
-{
-	memset(ra_events, 0, sizeof(ra_events));
-	return 1;
-}
-
-static struct file_operations ra_events_fops = {
-	.owner		= THIS_MODULE,
-	.open		= ra_events_open,
-	.write		= ra_events_write,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-};
-
 static int __init readahead_init(void)
 {
 	struct dentry *root;
+	int c, e;
 
 	root = debugfs_create_dir("readahead", NULL);
-
-	debugfs_create_file("events", 0644, root, NULL, &ra_events_fops);
-
-	debugfs_create_u32("debug_level", 0644, root, &readahead_debug_level);
 	debugfs_create_bool("disable_clock_readahead", 0644, root,
 			    &disable_clock_readahead);
 
+	for (e = 0; e < RA_EVENT_COUNT; e++) {
+		for (c = 0; c < RA_CLASS_COUNT; c++) {
+			int i = e * RA_CLASS_COUNT + c;
+			memcpy(&ra_stat_info[i], &ra_stat_info_template,
+			       sizeof(struct statistic_info));
+			scnprintf(ra_stat_name[i], RA_STAT_NAME_SIZE, "%s.%s",
+				  ra_event_name[e], ra_class_name[c]);
+			ra_stat_info[i].name = ra_stat_name[i];
+		}
+	}
+	statistic_create(&ra_stat_if, "readahead");
+
 	return 0;
 }