tools/vm/page_owner_sort: filter out unneeded line

Commit Message

Changhee Han April 29, 2020, 5:29 a.m. UTC

To see a sorted result from page owner, it needs a tiresome
preprocessing work before running page_owner_sort. This patch simply
filters out a line which starts with "PFN" while reading page owner
report.

Signed-off-by: Changhee Han <[e-mail]>
---
 Documentation/vm/page_owner.rst | 3 +--
 tools/vm/page_owner_sort.c      | 5 +++--
 2 files changed, 4 insertions(+), 4 deletions(-)

Patch

diff --git a/Documentation/vm/page_owner.rst b/Documentation/vm/page_owner.rst
index 0ed5ab8c7ab4..079f3f8c4784 100644
--- a/Documentation/vm/page_owner.rst
+++ b/Documentation/vm/page_owner.rst
@@ -83,8 +83,7 @@  Usage
 4) Analyze information from page owner::
 
 	cat /sys/kernel/debug/page_owner > page_owner_full.txt
-	grep -v ^PFN page_owner_full.txt > page_owner.txt
-	./page_owner_sort page_owner.txt sorted_page_owner.txt
+	./page_owner_sort page_owner_full.txt sorted_page_owner.txt
 
    See the result about who allocated each page
    in the ``sorted_page_owner.txt``.
diff --git a/tools/vm/page_owner_sort.c b/tools/vm/page_owner_sort.c
index d3a8755c039c..85eb65ea16d3 100644
--- a/tools/vm/page_owner_sort.c
+++ b/tools/vm/page_owner_sort.c
@@ -4,8 +4,7 @@ 
  *
  * Example use:
  * cat /sys/kernel/debug/page_owner > page_owner_full.txt
- * grep -v ^PFN page_owner_full.txt > page_owner.txt
- * ./page_owner_sort page_owner.txt sorted_page_owner.txt
+ * ./page_owner_sort page_owner_full.txt sorted_page_owner.txt
  *
  * See Documentation/vm/page_owner.rst
 */
@@ -38,6 +37,8 @@  int read_block(char *buf, int buf_size, FILE *fin)
 	while (buf_end - curr > 1 && fgets(curr, buf_end - curr, fin)) {
 		if (*curr == '\n') /* empty line */
 			return curr - buf;
+		if (!strncmp(curr, "PFN", 3))
+			continue;
 		curr += strlen(curr);
 	}