mm/zsmalloc: add trace events for zs_compact

Currently zsmalloc is widely used in android device.  Sometimes, we want
to see how frequently zs_compact is triggered or how may pages freed by
zs_compact(), or which zsmalloc pool is compacted.

We have backported the zs_compact() to our product(kernel 3.18).  It is
usefull for a longtime running device.  But there is not a convenient
way to get the detailed information of zs_comapct() which is usefull
for performance optimization.  Information about how much time
zs_compact used, which pool is compacted, how many page freed, etc.
With these information, we will know what is going on in zs_comapct.
And draw the relation between free mem and zs_comapct.

Most of the time, user can get the brief information from
trace_mm_shrink_slab_[start | end], but in some senario, they do not use
zsmalloc shrinker, but trigger compaction manually.  So add some trace
events in zs_compact is convenient.  Also we can add some zsmalloc
specific information(pool name, total compact pages, etc) in zsmalloc
trace.

This patch add two trace events for zs_compact(), below the trace log:
-----------------------------
root@land:/ # cat /d/tracing/trace
         kswapd0-125   [007] ...1   174.176979: zsmalloc_compact_start: pool zram0
         kswapd0-125   [007] ...1   174.181967: zsmalloc_compact_end: pool zram0: 608 pages compacted(total 1794)
         kswapd0-125   [000] ...1   184.134475: zsmalloc_compact_start: pool zram0
         kswapd0-125   [000] ...1   184.135010: zsmalloc_compact_end: pool zram0: 62 pages compacted(total 1856)
         kswapd0-125   [003] ...1   226.927221: zsmalloc_compact_start: pool zram0
         kswapd0-125   [003] ...1   226.928575: zsmalloc_compact_end: pool zram0: 250 pages compacted(total 2106)
-----------------------------

Link: http://lkml.kernel.org/r/1465289804-4913-1-git-send-email-opensource.ganesh@gmail.com
Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index b0bc023d25c5..10e15e884ca9 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -31,6 +31,8 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#define CREATE_TRACE_POINTS
+
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/sched.h>
@@ -53,6 +55,7 @@
 #include <linux/mount.h>
 #include <linux/migrate.h>
 #include <linux/pagemap.h>
+#include <trace/events/zsmalloc.h>
 
 #define ZSPAGE_MAGIC	0x58
 
@@ -2309,6 +2312,9 @@ unsigned long zs_compact(struct zs_pool *pool)
 {
 	int i;
 	struct size_class *class;
+	unsigned long pages_compacted_before = pool->stats.pages_compacted;
+
+	trace_zsmalloc_compact_start(pool->name);
 
 	for (i = zs_size_classes - 1; i >= 0; i--) {
 		class = pool->size_class[i];
@@ -2319,6 +2325,10 @@ unsigned long zs_compact(struct zs_pool *pool)
 		__zs_compact(pool, class);
 	}
 
+	trace_zsmalloc_compact_end(pool->name,
+		pool->stats.pages_compacted - pages_compacted_before,
+		pool->stats.pages_compacted);
+
 	return pool->stats.pages_compacted;
 }
 EXPORT_SYMBOL_GPL(zs_compact);