Re: [PATCH] Add tracepoints to track pagecache transition

Atsushi Tsuji
2009-02-17T11:05:02Z

Peter Zijlstra wrote:
> On Tue, 2009-02-17 at 18:00 +0900, Atsushi Tsuji wrote:
>
>> The below patch adds instrumentation for pagecache.
>
> And somehow you forgot to CC any of the mm people.. ;-)

Hi Peter,

Ah, sorry.
Thank you for adding to CC list.

>> +DECLARE_TRACE(filemap_add_to_page_cache,
>> + TPPROTO(struct address_space *mapping, pgoff_t offset),
>> + TPARGS(mapping, offset));
>> +DECLARE_TRACE(filemap_remove_from_page_cache,
>> + TPPROTO(struct address_space *mapping),
>> + TPARGS(mapping));
>
> This is rather asymmetric, why don't we care about the offset for the
> removed page?
>

Indeed.
I added the offset to the argument for the removed page and resend fixed patch.

Signed-off-by: Atsushi Tsuji <a-tsuji@bk.jp.nec.com>
---
diff --git a/include/trace/filemap.h b/include/trace/filemap.h
new file mode 100644
index 0000000..a17dc92
--- /dev/null
+++ b/include/trace/filemap.h
@@ -0,0 +1,13 @@
+#ifndef _TRACE_FILEMAP_H
+#define _TRACE_FILEMAP_H
+
+#include <linux/tracepoint.h>
+
+DECLARE_TRACE(filemap_add_to_page_cache,
+ TPPROTO(struct address_space *mapping, pgoff_t offset),
+ TPARGS(mapping, offset));
+DECLARE_TRACE(filemap_remove_from_page_cache,
+ TPPROTO(struct address_space *mapping, pgoff_t offset),
+ TPARGS(mapping, offset));
+
+#endif
diff --git a/mm/filemap.c b/mm/filemap.c
index 23acefe..23f75d2 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -34,6 +34,7 @@
#include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
#include <linux/memcontrol.h>
#include <linux/mm_inline.h> /* for page_is_file_cache() */
+#include <trace/filemap.h>
#include "internal.h"

/*
@@ -43,6 +44,8 @@

#include <asm/mman.h>

+DEFINE_TRACE(filemap_add_to_page_cache);
+DEFINE_TRACE(filemap_remove_from_page_cache);

/*
* Shared mappings implemented 30.11.1994. It's not fully working yet,
@@ -120,6 +123,7 @@ void __remove_from_page_cache(struct page *page)
page->mapping = NULL;
mapping->nrpages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
+ trace_filemap_remove_from_page_cache(mapping, page->index);
BUG_ON(page_mapped(page));
mem_cgroup_uncharge_cache_page(page);

@@ -475,6 +479,7 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
if (likely(!error)) {
mapping->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
+ trace_filemap_add_to_page_cache(mapping, offset);
} else {
page->mapping = NULL;
mem_cgroup_uncharge_cache_page(page);