Commit 60283726 authored by Jan Kara's avatar Jan Kara Committed by Andrew Morton
Browse files

readahead: add trace points 

Add a couple of trace points to make debugging readahead logic easier.

[jack@suse.cz: v2]
  Link: https://lkml.kernel.org/r/20250909145849.5090-2-jack@suse.cz
Link: https://lkml.kernel.org/r/20250908145533.31528-2-jack@suse.cz


Signed-off-by: default avatarJan Kara <jack@suse.cz>
Tested-by: default avatarPankaj Raghav <p.raghav@samsung.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e1831e8d

include/trace/events/readahead.h

0 → 100644
+132 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#undef TRACE_SYSTEM

#define TRACE_SYSTEM readahead



#if !defined(_TRACE_FILEMAP_H) || defined(TRACE_HEADER_MULTI_READ)

#define _TRACE_READAHEAD_H



#include <linux/types.h>

#include <linux/tracepoint.h>

#include <linux/mm.h>

#include <linux/fs.h>

#include <linux/pagemap.h>



TRACE_EVENT(page_cache_ra_unbounded,

	TP_PROTO(struct inode *inode, pgoff_t index, unsigned long nr_to_read,

		 unsigned long lookahead_size),



	TP_ARGS(inode, index, nr_to_read, lookahead_size),



	TP_STRUCT__entry(

		__field(unsigned long, i_ino)

		__field(dev_t, s_dev)

		__field(pgoff_t, index)

		__field(unsigned long, nr_to_read)

		__field(unsigned long, lookahead_size)

	),



	TP_fast_assign(

		__entry->i_ino = inode->i_ino;

		__entry->s_dev = inode->i_sb->s_dev;

		__entry->index = index;

		__entry->nr_to_read = nr_to_read;

		__entry->lookahead_size = lookahead_size;

	),



	TP_printk(

		"dev=%d:%d ino=%lx index=%lu nr_to_read=%lu lookahead_size=%lu",

		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,

		__entry->index, __entry->nr_to_read, __entry->lookahead_size

	)

);



TRACE_EVENT(page_cache_ra_order,

	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra),



	TP_ARGS(inode, index, ra),



	TP_STRUCT__entry(

		__field(unsigned long, i_ino)

		__field(dev_t, s_dev)

		__field(pgoff_t, index)

		__field(unsigned int, order)

		__field(unsigned int, size)

		__field(unsigned int, async_size)

		__field(unsigned int, ra_pages)

	),



	TP_fast_assign(

		__entry->i_ino = inode->i_ino;

		__entry->s_dev = inode->i_sb->s_dev;

		__entry->index = index;

		__entry->order = ra->order;

		__entry->size = ra->size;

		__entry->async_size = ra->async_size;

		__entry->ra_pages = ra->ra_pages;

	),



	TP_printk(

		"dev=%d:%d ino=%lx index=%lu order=%u size=%u async_size=%u ra_pages=%u",

		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,

		__entry->index, __entry->order, __entry->size,

		__entry->async_size, __entry->ra_pages

	)

);



DECLARE_EVENT_CLASS(page_cache_ra_op,

	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,

		 unsigned long req_count),



	TP_ARGS(inode, index, ra, req_count),



	TP_STRUCT__entry(

		__field(unsigned long, i_ino)

		__field(dev_t, s_dev)

		__field(pgoff_t, index)

		__field(unsigned int, order)

		__field(unsigned int, size)

		__field(unsigned int, async_size)

		__field(unsigned int, ra_pages)

		__field(unsigned int, mmap_miss)

		__field(loff_t, prev_pos)

		__field(unsigned long, req_count)

	),



	TP_fast_assign(

		__entry->i_ino = inode->i_ino;

		__entry->s_dev = inode->i_sb->s_dev;

		__entry->index = index;

		__entry->order = ra->order;

		__entry->size = ra->size;

		__entry->async_size = ra->async_size;

		__entry->ra_pages = ra->ra_pages;

		__entry->mmap_miss = ra->mmap_miss;

		__entry->prev_pos = ra->prev_pos;

		__entry->req_count = req_count;

	),



	TP_printk(

		"dev=%d:%d ino=%lx index=%lu req_count=%lu order=%u size=%u async_size=%u ra_pages=%u mmap_miss=%u prev_pos=%lld",

		MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,

		__entry->index, __entry->req_count, __entry->order,

		__entry->size, __entry->async_size, __entry->ra_pages,

		__entry->mmap_miss, __entry->prev_pos

	)

);



DEFINE_EVENT(page_cache_ra_op, page_cache_sync_ra,

	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,

		 unsigned long req_count),

	TP_ARGS(inode, index, ra, req_count)

);



DEFINE_EVENT(page_cache_ra_op, page_cache_async_ra,

	TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,

		 unsigned long req_count),

	TP_ARGS(inode, index, ra, req_count)

);



#endif /* _TRACE_FILEMAP_H */



/* This part must be outside protection */

#include <trace/define_trace.h>

mm/readahead.c

+8 −0
Original line number Diff line number Diff line
@@ -129,6 +129,9 @@ 
#include <linux/fadvise.h>

#include <linux/sched/mm.h>



#define CREATE_TRACE_POINTS

#include <trace/events/readahead.h>



#include "internal.h"



/*
@@ -225,6 +228,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, 
	 */

	unsigned int nofs = memalloc_nofs_save();



	trace_page_cache_ra_unbounded(mapping->host, index, nr_to_read,

				      lookahead_size);

	filemap_invalidate_lock_shared(mapping);

	index = mapping_align_index(mapping, index);
@@ -470,6 +475,7 @@ void page_cache_ra_order(struct readahead_control *ractl, 
	gfp_t gfp = readahead_gfp_mask(mapping);

	unsigned int new_order = ra->order;



	trace_page_cache_ra_order(mapping->host, start, ra);

	if (!mapping_large_folio_support(mapping)) {

		ra->order = 0;

		goto fallback;
@@ -554,6 +560,7 @@ void page_cache_sync_ra(struct readahead_control *ractl, 
	unsigned long max_pages, contig_count;

	pgoff_t prev_index, miss;



	trace_page_cache_sync_ra(ractl->mapping->host, index, ra, req_count);

	/*

	 * Even if readahead is disabled, issue this request as readahead

	 * as we'll need it to satisfy the requested range. The forced
@@ -638,6 +645,7 @@ void page_cache_async_ra(struct readahead_control *ractl, 
	if (folio_test_writeback(folio))

		return;



	trace_page_cache_async_ra(ractl->mapping->host, index, ra, req_count);

	folio_clear_readahead(folio);



	if (blk_cgroup_congested())