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jankaraakpm00
jankara
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akpm00
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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: Jan Kara <jack@suse.cz> Tested-by: Pankaj Raghav <p.raghav@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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‎include/trace/events/readahead.h‎

Lines changed: 132 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,132 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#undef TRACE_SYSTEM
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#define TRACE_SYSTEM readahead
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#if !defined(_TRACE_FILEMAP_H) || defined(TRACE_HEADER_MULTI_READ)
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#define _TRACE_READAHEAD_H
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8+
#include <linux/types.h>
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#include <linux/tracepoint.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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14+
TRACE_EVENT(page_cache_ra_unbounded,
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TP_PROTO(struct inode *inode, pgoff_t index, unsigned long nr_to_read,
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unsigned long lookahead_size),
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TP_ARGS(inode, index, nr_to_read, lookahead_size),
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TP_STRUCT__entry(
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__field(unsigned long, i_ino)
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__field(dev_t, s_dev)
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__field(pgoff_t, index)
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__field(unsigned long, nr_to_read)
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__field(unsigned long, lookahead_size)
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),
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TP_fast_assign(
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__entry->i_ino = inode->i_ino;
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__entry->s_dev = inode->i_sb->s_dev;
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__entry->index = index;
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__entry->nr_to_read = nr_to_read;
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__entry->lookahead_size = lookahead_size;
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),
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TP_printk(
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"dev=%d:%d ino=%lx index=%lu nr_to_read=%lu lookahead_size=%lu",
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MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
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__entry->index, __entry->nr_to_read, __entry->lookahead_size
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)
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);
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TRACE_EVENT(page_cache_ra_order,
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TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra),
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TP_ARGS(inode, index, ra),
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TP_STRUCT__entry(
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__field(unsigned long, i_ino)
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__field(dev_t, s_dev)
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__field(pgoff_t, index)
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__field(unsigned int, order)
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__field(unsigned int, size)
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__field(unsigned int, async_size)
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__field(unsigned int, ra_pages)
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),
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TP_fast_assign(
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__entry->i_ino = inode->i_ino;
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__entry->s_dev = inode->i_sb->s_dev;
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__entry->index = index;
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__entry->order = ra->order;
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__entry->size = ra->size;
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__entry->async_size = ra->async_size;
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__entry->ra_pages = ra->ra_pages;
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),
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TP_printk(
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"dev=%d:%d ino=%lx index=%lu order=%u size=%u async_size=%u ra_pages=%u",
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MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
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__entry->index, __entry->order, __entry->size,
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__entry->async_size, __entry->ra_pages
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)
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);
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DECLARE_EVENT_CLASS(page_cache_ra_op,
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TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
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unsigned long req_count),
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TP_ARGS(inode, index, ra, req_count),
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TP_STRUCT__entry(
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__field(unsigned long, i_ino)
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__field(dev_t, s_dev)
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__field(pgoff_t, index)
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__field(unsigned int, order)
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__field(unsigned int, size)
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__field(unsigned int, async_size)
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__field(unsigned int, ra_pages)
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__field(unsigned int, mmap_miss)
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__field(loff_t, prev_pos)
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__field(unsigned long, req_count)
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),
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TP_fast_assign(
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__entry->i_ino = inode->i_ino;
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__entry->s_dev = inode->i_sb->s_dev;
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__entry->index = index;
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__entry->order = ra->order;
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__entry->size = ra->size;
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__entry->async_size = ra->async_size;
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__entry->ra_pages = ra->ra_pages;
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__entry->mmap_miss = ra->mmap_miss;
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__entry->prev_pos = ra->prev_pos;
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__entry->req_count = req_count;
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),
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TP_printk(
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"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",
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MAJOR(__entry->s_dev), MINOR(__entry->s_dev), __entry->i_ino,
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__entry->index, __entry->req_count, __entry->order,
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__entry->size, __entry->async_size, __entry->ra_pages,
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__entry->mmap_miss, __entry->prev_pos
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)
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);
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DEFINE_EVENT(page_cache_ra_op, page_cache_sync_ra,
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TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
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unsigned long req_count),
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TP_ARGS(inode, index, ra, req_count)
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);
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DEFINE_EVENT(page_cache_ra_op, page_cache_async_ra,
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TP_PROTO(struct inode *inode, pgoff_t index, struct file_ra_state *ra,
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unsigned long req_count),
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TP_ARGS(inode, index, ra, req_count)
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);
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#endif /* _TRACE_FILEMAP_H */
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/* This part must be outside protection */
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#include <trace/define_trace.h>

‎mm/readahead.c‎

Lines changed: 8 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -129,6 +129,9 @@
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#include <linux/fadvise.h>
130130
#include <linux/sched/mm.h>
131131

132+
#define CREATE_TRACE_POINTS
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#include <trace/events/readahead.h>
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132135
#include "internal.h"
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134137
/*
@@ -225,6 +228,8 @@ void page_cache_ra_unbounded(struct readahead_control *ractl,
225228
*/
226229
unsigned int nofs = memalloc_nofs_save();
227230

231+
trace_page_cache_ra_unbounded(mapping->host, index, nr_to_read,
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lookahead_size);
228233
filemap_invalidate_lock_shared(mapping);
229234
index = mapping_align_index(mapping, index);
230235

@@ -470,6 +475,7 @@ void page_cache_ra_order(struct readahead_control *ractl,
470475
gfp_t gfp = readahead_gfp_mask(mapping);
471476
unsigned int new_order = ra->order;
472477

478+
trace_page_cache_ra_order(mapping->host, start, ra);
473479
if (!mapping_large_folio_support(mapping)) {
474480
ra->order = 0;
475481
goto fallback;
@@ -554,6 +560,7 @@ void page_cache_sync_ra(struct readahead_control *ractl,
554560
unsigned long max_pages, contig_count;
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pgoff_t prev_index, miss;
556562

563+
trace_page_cache_sync_ra(ractl->mapping->host, index, ra, req_count);
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/*
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* Even if readahead is disabled, issue this request as readahead
559566
* 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,
638645
if (folio_test_writeback(folio))
639646
return;
640647

648+
trace_page_cache_async_ra(ractl->mapping->host, index, ra, req_count);
641649
folio_clear_readahead(folio);
642650

643651
if (blk_cgroup_congested())

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