mm: trace filemap add and del

Use the events API to trace filemap loading and unloading of file pieces
into the page cache.

This patch aims at tracing the eviction reload cycle of executable and
shared libraries pages in a memory constrained environment.

The typical usage is to spot a specific device and inode (for example
/lib/libc.so) to see the eviction cycles, and find out if frequently
used code is rather spread across many pages (bad) or coallesced (good).

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 58 insertions, 0 deletions

diff --git a/include/trace/events/filemap.h b/include/trace/events/filemap.h
new file mode 100644
index 00000000000..0421f49a20f
--- /dev/null
+++ b/include/trace/events/filemap.h
@@ -0,0 +1,58 @@
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM filemap
+
+#if !defined(_TRACE_FILEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_FILEMAP_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+#include <linux/mm.h>
+#include <linux/memcontrol.h>
+#include <linux/device.h>
+#include <linux/kdev_t.h>
+
+DECLARE_EVENT_CLASS(mm_filemap_op_page_cache,
+
+	TP_PROTO(struct page *page),
+
+	TP_ARGS(page),
+
+	TP_STRUCT__entry(
+		__field(struct page *, page)
+		__field(unsigned long, i_ino)
+		__field(unsigned long, index)
+		__field(dev_t, s_dev)
+	),
+
+	TP_fast_assign(
+		__entry->page = page;
+		__entry->i_ino = page->mapping->host->i_ino;
+		__entry->index = page->index;
+		if (page->mapping->host->i_sb)
+			__entry->s_dev = page->mapping->host->i_sb->s_dev;
+		else
+			__entry->s_dev = page->mapping->host->i_rdev;
+	),
+
+	TP_printk("dev %d:%d ino %lx page=%p pfn=%lu ofs=%lu",
+		MAJOR(__entry->s_dev), MINOR(__entry->s_dev),
+		__entry->i_ino,
+		__entry->page,
+		page_to_pfn(__entry->page),
+		__entry->index << PAGE_SHIFT)
+);
+
+DEFINE_EVENT(mm_filemap_op_page_cache, mm_filemap_delete_from_page_cache,
+	TP_PROTO(struct page *page),
+	TP_ARGS(page)
+	);
+
+DEFINE_EVENT(mm_filemap_op_page_cache, mm_filemap_add_to_page_cache,
+	TP_PROTO(struct page *page),
+	TP_ARGS(page)
+	);
+
+#endif /* _TRACE_FILEMAP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>