On Thu, 2013-02-28 at 21:47 +0100, Robert Jarzmik wrote:
> 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@xxxxxxx>
> Cc: Dave Chinner <david@xxxxxxxxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> include/trace/events/filemap.h | 79 ++++++++++++++++++++++++++++++++++++++++
> mm/filemap.c | 5 +++
> 2 files changed, 84 insertions(+)
> create mode 100644 include/trace/events/filemap.h
>
> diff --git a/include/trace/events/filemap.h b/include/trace/events/filemap.h
> new file mode 100644
> index 0000000..2d36386
> --- /dev/null
> +++ b/include/trace/events/filemap.h
> @@ -0,0 +1,79 @@
> +#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>
> +
> +TRACE_EVENT(mm_filemap_delete_from_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)
> +);
> +
> +TRACE_EVENT(mm_filemap_add_to_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)
> +);
The above two events are identical. Please use DECLARE_EVENT_CLASS()
DEFINE_EVENT() for them. It saves a lot of excess created code.
-- Steve
> +
> +#endif /* _TRACE_FILEMAP_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index e1979fd..6ed13fc 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -35,6 +35,9 @@
> #include <linux/cleancache.h>
> #include "internal.h"
>
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/filemap.h>
> +
> /*
> * FIXME: remove all knowledge of the buffer layer from the core VM
> */
> @@ -113,6 +116,7 @@ void __delete_from_page_cache(struct page *page)
> {
> struct address_space *mapping = page->mapping;
>
> + trace_mm_filemap_delete_from_page_cache(page);
> /*
> * if we're uptodate, flush out into the cleancache, otherwise
> * invalidate any existing cleancache entries. We can't leave
> @@ -463,6 +467,7 @@ 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_mm_filemap_add_to_page_cache(page);
> spin_unlock_irq(&mapping->tree_lock);
> } else {
> page->mapping = NULL;
--
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