[PATCH] mm/zsmalloc: add trace events for zs_compact

Ganesh Mahendran
2016-06-07T08:57:20Z

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.

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)
-----------------------------

Signed-off-by: Ganesh Mahendran <opensource.ganesh@gmail.com>
---
include/trace/events/zsmalloc.h | 56 +++++++++++++++++++++++++++++++++++++++++
mm/zsmalloc.c | 10 ++++++++
2 files changed, 66 insertions(+)
create mode 100644 include/trace/events/zsmalloc.h

diff --git a/include/trace/events/zsmalloc.h b/include/trace/events/zsmalloc.h
new file mode 100644
index 0000000..3b6f14e
--- /dev/null
+++ b/include/trace/events/zsmalloc.h
@@ -0,0 +1,56 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM zsmalloc
+
+#if !defined(_TRACE_ZSMALLOC_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_ZSMALLOC_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(zsmalloc_compact_start,
+
+ TP_PROTO(const char *pool_name),
+
+ TP_ARGS(pool_name),
+
+ TP_STRUCT__entry(
+ __field(const char *, pool_name)
+ ),
+
+ TP_fast_assign(
+ __entry->pool_name = pool_name;
+ ),
+
+ TP_printk("pool %s",
+ __entry->pool_name)
+);
+
+TRACE_EVENT(zsmalloc_compact_end,
+
+ TP_PROTO(const char *pool_name, unsigned long pages_compacted,
+ unsigned long pages_total_compacted),
+
+ TP_ARGS(pool_name, pages_compacted, pages_total_compacted),
+
+ TP_STRUCT__entry(
+ __field(const char *, pool_name)
+ __field(unsigned long, pages_compacted)
+ __field(unsigned long, pages_total_compacted)
+ ),
+
+ TP_fast_assign(
+ __entry->pool_name = pool_name;
+ __entry->pages_compacted = pages_compacted;
+ __entry->pages_total_compacted = pages_total_compacted;
+ ),
+
+ TP_printk("pool %s: %ld pages compacted(total %ld)",
+ __entry->pool_name,
+ __entry->pages_compacted,
+ __entry->pages_total_compacted)
+);
+
+#endif /* _TRACE_ZSMALLOC_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
index 213d0e1..441b9f7 100644
--- a/mm/zsmalloc.c
+++ b/mm/zsmalloc.c
@@ -30,6 +30,8 @@

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

+#define CREATE_TRACE_POINTS
+
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
@@ -52,6 +54,7 @@
#include <linux/mount.h>
#include <linux/compaction.h>
#include <linux/pagemap.h>
+#include <trace/events/zsmalloc.h>

#define ZSPAGE_MAGIC 0x58

@@ -2330,6 +2333,9 @@ 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];
@@ -2340,6 +2346,10 @@ 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);
--
1.9.1