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readahead: add trace points

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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: Jan Kara <jack@suse.cz>
Tested-by: Pankaj Raghav <p.raghav@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Jan Kara
2025-09-08 16:55:34 +02:00
committed by Andrew Morton
parent e1831e8dd1
commit 6028372689
2 changed files with 140 additions and 0 deletions
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132
include/trace/events/readahead.h Normal file
View File

@@ -0,0 +1,132 @@
/* 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>

8
mm/readahead.c
View File

@@ -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())