tools/vm/page_owner_sort.c: count and sort by mem

When viewing page owner information, we may be more concerned about the
total memory rather than the times of stack appears. Therefore, the
following adjustments are made:

1. Added the statistics on the total number of pages.

2. Added the optional parameter "-m" to configure the program to sort by
memory (total pages).

The general output of page_owner is as follows:

Page allocated via order XXX, ...
PFN XXX ...
// Detailed stack

Page allocated via order XXX, ...
PFN XXX ...
// Detailed stack

The original page_owner_sort ignores PFN rows, puts the remaining rows
in buf, counts the times of buf, and finally sorts them according to the
times. General output:

XXX times:
Page allocated via order XXX, ...
// Detailed stack

Now, we use regexp to extract the page order value from the buf, and
count the total pages for the buf. General output:

XXX times, XXX pages:
Page allocated via order XXX, ...
// Detailed stack

By default, it is still sorted by the times of buf; If you want to sort
by the pages nums of buf, use the new -m parameter.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Zhenliang Wei <[e-mail]>
Cc: Tang Bin <[e-mail]>
Cc: Zhang Shengju <[e-mail]>
Cc: Zhenliang Wei <[e-mail]>
Cc: Xiaoming Ni <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/vm/page_owner.rst

···
 	cat /sys/kernel/debug/page_owner > page_owner_full.txt
 	./page_owner_sort page_owner_full.txt sorted_page_owner.txt
 
+   The general output of ``page_owner_full.txt`` is as follows:
+
+	Page allocated via order XXX, ...
+	PFN XXX ...
+	 // Detailed stack
+
+	Page allocated via order XXX, ...
+	PFN XXX ...
+	 // Detailed stack
+
+   The ``page_owner_sort`` tool ignores ``PFN`` rows, puts the remaining rows
+   in buf, uses regexp to extract the page order value, counts the times
+   and pages of buf, and finally sorts them according to the times.
+
    See the result about who allocated each page
-   in the ``sorted_page_owner.txt``.
+   in the ``sorted_page_owner.txt``. General output:
+
+	XXX times, XXX pages:
+	Page allocated via order XXX, ...
+	 // Detailed stack
+
+   By default, ``page_owner_sort`` is sorted according to the times of buf.
+   If you want to sort by the pages nums of buf, use the ``-m`` parameter.

tools/vm/page_owner_sort.c

···
  * Example use:
  * cat /sys/kernel/debug/page_owner > page_owner_full.txt
  * ./page_owner_sort page_owner_full.txt sorted_page_owner.txt
+ * Or sort by total memory:
+ * ./page_owner_sort -m page_owner_full.txt sorted_page_owner.txt
  *
  * See Documentation/vm/page_owner.rst
 */
···
 #include <fcntl.h>
 #include <unistd.h>
 #include <string.h>
+#include <regex.h>
+#include <errno.h>
 
 struct block_list {
 	char *txt;
 	int len;
 	int num;
+	int page_num;
 };
 
-
+static int sort_by_memory;
+static regex_t order_pattern;
 static struct block_list *list;
 static int list_size;
 static int max_size;
···
 	return l2->num - l1->num;
 }
 
+static int compare_page_num(const void *p1, const void *p2)
+{
+	const struct block_list *l1 = p1, *l2 = p2;
+
+	return l2->page_num - l1->page_num;
+}
+
+static int get_page_num(char *buf)
+{
+	int err, val_len, order_val;
+	char order_str[4] = {0};
+	char *endptr;
+	regmatch_t pmatch[2];
+
+	err = regexec(&order_pattern, buf, 2, pmatch, REG_NOTBOL);
+	if (err != 0 || pmatch[1].rm_so == -1) {
+		printf("no order pattern in %s\n", buf);
+		return 0;
+	}
+	val_len = pmatch[1].rm_eo - pmatch[1].rm_so;
+	if (val_len > 2) /* max_order should not exceed 2 digits */
+		goto wrong_order;
+
+	memcpy(order_str, buf + pmatch[1].rm_so, val_len);
+
+	errno = 0;
+	order_val = strtol(order_str, &endptr, 10);
+	if (errno != 0 || endptr == order_str || *endptr != '\0')
+		goto wrong_order;
+
+	return 1 << order_val;
+
+wrong_order:
+	printf("wrong order in follow buf:\n%s\n", buf);
+	return 0;
+}
+
 static void add_list(char *buf, int len)
 {
 	if (list_size != 0 &&
 	    len == list[list_size-1].len &&
 	    memcmp(buf, list[list_size-1].txt, len) == 0) {
 		list[list_size-1].num++;
+		list[list_size-1].page_num += get_page_num(buf);
 		return;
 	}
 	if (list_size == max_size) {
···
 	list[list_size].txt = malloc(len+1);
 	list[list_size].len = len;
 	list[list_size].num = 1;
+	list[list_size].page_num = get_page_num(buf);
 	memcpy(list[list_size].txt, buf, len);
 	list[list_size].txt[len] = 0;
 	list_size++;
···
 
 #define BUF_SIZE	(128 * 1024)
 
+static void usage(void)
+{
+	printf("Usage: ./page_owner_sort [-m] <input> <output>\n"
+		"-m	Sort by total memory. If this option is unset, sort by times\n"
+	);
+}
+
 int main(int argc, char **argv)
 {
 	FILE *fin, *fout;
···
 	int ret, i, count;
 	struct block_list *list2;
 	struct stat st;
+	int err;
+	int opt;
 
-	if (argc < 3) {
-		printf("Usage: ./program <input> <output>\n");
+	while ((opt = getopt(argc, argv, "m")) != -1)
+		switch (opt) {
+		case 'm':
+			sort_by_memory = 1;
+			break;
+		default:
+			usage();
+			exit(1);
+		}
+
+	if (optind >= (argc - 1)) {
+		usage();
+		exit(1);
+	}
+
+	fin = fopen(argv[optind], "r");
+	fout = fopen(argv[optind + 1], "w");
+	if (!fin || !fout) {
+		usage();
 		perror("open: ");
 		exit(1);
 	}
 
-	fin = fopen(argv[1], "r");
-	fout = fopen(argv[2], "w");
-	if (!fin || !fout) {
-		printf("Usage: ./program <input> <output>\n");
-		perror("open: ");
+	err = regcomp(&order_pattern, "order\\s*([0-9]*),", REG_EXTENDED|REG_NEWLINE);
+	if (err != 0 || order_pattern.re_nsub != 1) {
+		printf("%s: Invalid pattern 'order\\s*([0-9]*),' code %d\n",
+			argv[0], err);
 		exit(1);
 	}
 
···
 			list2[count++] = list[i];
 		} else {
 			list2[count-1].num += list[i].num;
+			list2[count-1].page_num += list[i].page_num;
 		}
 	}
 
-	qsort(list2, count, sizeof(list[0]), compare_num);
+	if (sort_by_memory)
+		qsort(list2, count, sizeof(list[0]), compare_page_num);
+	else
+		qsort(list2, count, sizeof(list[0]), compare_num);
 
 	for (i = 0; i < count; i++)
-		fprintf(fout, "%d times:\n%s\n", list2[i].num, list2[i].txt);
+		fprintf(fout, "%d times, %d pages:\n%s\n",
+				list2[i].num, list2[i].page_num, list2[i].txt);
 
+	regfree(&order_pattern);
 	return 0;
 }