Re: [RFC PATCH -tip 1/2 v2] add tracepoints for pagecache

[Steven Rostedt]

On Fri, 2010-01-22 at 19:07 -0500, Keiichi KII wrote:
> This patch adds several tracepoints to track pagecach behavior.
> These trecepoints would help us monitor pagecache usage with high resolution.
> 
> Signed-off-by: Keiichi Kii <k-keiichi@xxxxxxxxxxxxx>
> Cc: Atsushi Tsuji <a-tsuji@xxxxxxxxxxxxx> 
> ---
>  include/trace/events/filemap.h |   83 +++++++++++++++++++++++++++++++++++++++++
>  mm/filemap.c                   |    5 ++
>  mm/truncate.c                  |    2 
>  mm/vmscan.c                    |    3 +
>  4 files changed, 93 insertions(+)
> 
> Index: linux-2.6-tip/include/trace/events/filemap.h
> ===================================================================
> --- /dev/null
> +++ linux-2.6-tip/include/trace/events/filemap.h
> @@ -0,0 +1,83 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM filemap
> +
> +#if !defined(_TRACE_FILEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_FILEMAP_H
> +
> +#include <linux/fs.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(find_get_page,
> +
> +	TP_PROTO(struct address_space *mapping, pgoff_t offset,
> +		struct page *page),
> +
> +	TP_ARGS(mapping, offset, page),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t, s_dev)
> +		__field(ino_t, i_ino)
> +		__field(pgoff_t, offset)
> +		__field(struct page *, page)
> +		),
> +
> +	TP_fast_assign(
> +		__entry->s_dev = mapping->host ? mapping->host->i_sb->s_dev : 0;
> +		__entry->i_ino = mapping->host ? mapping->host->i_ino : 0;
> +		__entry->offset = offset;
> +		__entry->page = page;
> +		),
> +
> +	TP_printk("s_dev=%u:%u i_ino=%lu offset=%lu %s", MAJOR(__entry->s_dev),
> +		MINOR(__entry->s_dev), __entry->i_ino, __entry->offset,
> +		__entry->page == NULL ? "page_not_found" : "page_found")
> +);
> +
> +TRACE_EVENT(add_to_page_cache,
> +
> +	TP_PROTO(struct address_space *mapping, pgoff_t offset),
> +
> +	TP_ARGS(mapping, offset),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t, s_dev)
> +		__field(ino_t, i_ino)
> +		__field(pgoff_t, offset)
> +		),
> +
> +	TP_fast_assign(
> +		__entry->s_dev = mapping->host->i_sb->s_dev;
> +		__entry->i_ino = mapping->host->i_ino;
> +		__entry->offset = offset;
> +		),
> +
> +	TP_printk("s_dev=%u:%u i_ino=%lu offset=%lu", MAJOR(__entry->s_dev),
> +		MINOR(__entry->s_dev), __entry->i_ino, __entry->offset)
> +);
> +
> +TRACE_EVENT(remove_from_page_cache,
> +
> +	TP_PROTO(struct address_space *mapping, pgoff_t offset),
> +
> +	TP_ARGS(mapping, offset),
> +
> +	TP_STRUCT__entry(
> +		__field(dev_t, s_dev)
> +		__field(ino_t, i_ino)
> +		__field(pgoff_t, offset)
> +		),
> +
> +	TP_fast_assign(
> +		__entry->s_dev = mapping->host->i_sb->s_dev;
> +		__entry->i_ino = mapping->host->i_ino;
> +		__entry->offset = offset;
> +		),
> +
> +	TP_printk("s_dev=%u:%u i_ino=%lu offset=%lu", MAJOR(__entry->s_dev),
> +		MINOR(__entry->s_dev), __entry->i_ino, __entry->offset)
> +);
> +

The above qualify in converting to templates or DECLACE_TRACE_CLASS, and
DEFINE_EVENT, That is, rename the above TRACE_EVENT into
DECLARE_TRACE_CLASS, and then have the other one be a DEFINE_EVENT().
See the trace/event/sched.h for examples.

The TRACE_EVENT can add a bit of code, so use DECLARE_TRACE_CLASS when
possible and it will save on the size overhead.

-- Steve

> +#endif /* _TRACE_FILEMAP_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> Index: linux-2.6-tip/mm/filemap.c
> ===================================================================
> --- linux-2.6-tip.orig/mm/filemap.c
> +++ linux-2.6-tip/mm/filemap.c
> @@ -34,6 +34,8 @@
>  #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
>  #include <linux/memcontrol.h>
>  #include <linux/mm_inline.h> /* for page_is_file_cache() */
> +#define CREATE_TRACE_POINTS
> +#include <trace/events/filemap.h>
>  #include "internal.h"
>  
>  /*
> @@ -149,6 +151,7 @@ void remove_from_page_cache(struct page 
>  	spin_lock_irq(&mapping->tree_lock);
>  	__remove_from_page_cache(page);
>  	spin_unlock_irq(&mapping->tree_lock);
> +	trace_remove_from_page_cache(mapping, page->index);
>  	mem_cgroup_uncharge_cache_page(page);
>  }
>  
> @@ -419,6 +422,7 @@ int add_to_page_cache_locked(struct page
>  			if (PageSwapBacked(page))
>  				__inc_zone_page_state(page, NR_SHMEM);
>  			spin_unlock_irq(&mapping->tree_lock);
> +			trace_add_to_page_cache(mapping, offset);
>  		} else {
>  			page->mapping = NULL;
>  			spin_unlock_irq(&mapping->tree_lock);
> @@ -642,6 +646,7 @@ repeat:
>  	}
>  	rcu_read_unlock();
>  
> +	trace_find_get_page(mapping, offset, page);
>  	return page;
>  }
>  EXPORT_SYMBOL(find_get_page);
> Index: linux-2.6-tip/mm/truncate.c
> ===================================================================
> --- linux-2.6-tip.orig/mm/truncate.c
> +++ linux-2.6-tip/mm/truncate.c
> @@ -20,6 +20,7 @@
>  				   do_invalidatepage */
>  #include "internal.h"
>  
> +#include <trace/events/filemap.h>
>  
>  /**
>   * do_invalidatepage - invalidate part or all of a page
> @@ -388,6 +389,7 @@ invalidate_complete_page2(struct address
>  	BUG_ON(page_has_private(page));
>  	__remove_from_page_cache(page);
>  	spin_unlock_irq(&mapping->tree_lock);
> +	trace_remove_from_page_cache(mapping, page->index);
>  	mem_cgroup_uncharge_cache_page(page);
>  	page_cache_release(page);	/* pagecache ref */
>  	return 1;
> Index: linux-2.6-tip/mm/vmscan.c
> ===================================================================
> --- linux-2.6-tip.orig/mm/vmscan.c
> +++ linux-2.6-tip/mm/vmscan.c
> @@ -48,6 +48,8 @@
>  
>  #include "internal.h"
>  
> +#include <trace/events/filemap.h>
> +
>  struct scan_control {
>  	/* Incremented by the number of inactive pages that were scanned */
>  	unsigned long nr_scanned;
> @@ -477,6 +479,7 @@ static int __remove_mapping(struct addre
>  	} else {
>  		__remove_from_page_cache(page);
>  		spin_unlock_irq(&mapping->tree_lock);
> +		trace_remove_from_page_cache(mapping, page->index);
>  		mem_cgroup_uncharge_cache_page(page);
>  	}
>  
> 
> 


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