Re: [PATCH RESEND] mm: trace filemap add and del

[Steven Rostedt <rostedt@goodmis.org>]

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@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>
> ---
>  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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