btrfs: add tracepoints for extent map shrinker events

Add some tracepoints for the extent map shrinker to help debug and analyse
main events. These have proved useful during development of the shrinker.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 62a21491c04404b263eea53db06d68ba11819e95..744e8952abb04d4a3651ee780463f306d5ec8a40 100644 (file)
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1080,6 +1080,7 @@ static long btrfs_scan_inode(struct btrfs_inode *inode, long *scanned, long nr_t
                        btrfs_set_inode_full_sync(inode);
 
                remove_extent_mapping(inode, em);
+               trace_btrfs_extent_map_shrinker_remove_em(inode, em);
                /* Drop the reference for the tree. */
                free_extent_map(em);
                nr_dropped++;
@@ -1152,6 +1153,12 @@ long btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan)
        long nr_dropped = 0;
        long scanned = 0;
 
+       if (trace_btrfs_extent_map_shrinker_scan_enter_enabled()) {
+               s64 nr = percpu_counter_sum_positive(&fs_info->evictable_extent_maps);
+
+               trace_btrfs_extent_map_shrinker_scan_enter(fs_info, nr_to_scan, nr);
+       }
+
        while (scanned < nr_to_scan) {
                struct btrfs_root *root;
                unsigned long count;
@@ -1184,5 +1191,11 @@ long btrfs_free_extent_maps(struct btrfs_fs_info *fs_info, long nr_to_scan)
                btrfs_put_root(root);
        }
 
+       if (trace_btrfs_extent_map_shrinker_scan_exit_enabled()) {
+               s64 nr = percpu_counter_sum_positive(&fs_info->evictable_extent_maps);
+
+               trace_btrfs_extent_map_shrinker_scan_exit(fs_info, nr_dropped, nr);
+       }
+
        return nr_dropped;
 }

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 571f90d18c7f6a923eac556cb5b0c5fbaf04a6a2..2dbc930a20f77131e96a5bfd048c00b9d2be0e20 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -2374,8 +2374,11 @@ static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
 static long btrfs_nr_cached_objects(struct super_block *sb, struct shrink_control *sc)
 {
        struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+       const s64 nr = percpu_counter_sum_positive(&fs_info->evictable_extent_maps);
 
-       return percpu_counter_sum_positive(&fs_info->evictable_extent_maps);
+       trace_btrfs_extent_map_shrinker_count(fs_info, nr);
+
+       return nr;
 }
 
 static long btrfs_free_cached_objects(struct super_block *sb, struct shrink_control *sc)

diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h
index 8f2497603cb5bad2bf1082b40e5684fe16da7d1a..d2d94d7c3fb598d4efed5f08da09963be4e0a146 100644 (file)
--- a/include/trace/events/btrfs.h
+++ b/include/trace/events/btrfs.h
@@ -2537,6 +2537,105 @@ TRACE_EVENT(btrfs_get_raid_extent_offset,
                        __entry->devid)
 );
 
+TRACE_EVENT(btrfs_extent_map_shrinker_count,
+
+       TP_PROTO(const struct btrfs_fs_info *fs_info, long nr),
+
+       TP_ARGS(fs_info, nr),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        long,   nr      )
+       ),
+
+       TP_fast_assign_btrfs(fs_info,
+               __entry->nr             = nr;
+       ),
+
+       TP_printk_btrfs("nr=%ld", __entry->nr)
+);
+
+TRACE_EVENT(btrfs_extent_map_shrinker_scan_enter,
+
+       TP_PROTO(const struct btrfs_fs_info *fs_info, long nr_to_scan, long nr),
+
+       TP_ARGS(fs_info, nr_to_scan, nr),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        long,   nr_to_scan      )
+               __field(        long,   nr              )
+               __field(        u64,    last_root_id    )
+               __field(        u64,    last_ino        )
+       ),
+
+       TP_fast_assign_btrfs(fs_info,
+               __entry->nr_to_scan     = nr_to_scan;
+               __entry->nr             = nr;
+               __entry->last_root_id   = fs_info->extent_map_shrinker_last_root;
+               __entry->last_ino       = fs_info->extent_map_shrinker_last_ino;
+       ),
+
+       TP_printk_btrfs("nr_to_scan=%ld nr=%ld last_root=%llu(%s) last_ino=%llu",
+                       __entry->nr_to_scan, __entry->nr,
+                       show_root_type(__entry->last_root_id), __entry->last_ino)
+);
+
+TRACE_EVENT(btrfs_extent_map_shrinker_scan_exit,
+
+       TP_PROTO(const struct btrfs_fs_info *fs_info, long nr_dropped, long nr),
+
+       TP_ARGS(fs_info, nr_dropped, nr),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        long,   nr_dropped      )
+               __field(        long,   nr              )
+               __field(        u64,    last_root_id    )
+               __field(        u64,    last_ino        )
+       ),
+
+       TP_fast_assign_btrfs(fs_info,
+               __entry->nr_dropped     = nr_dropped;
+               __entry->nr             = nr;
+               __entry->last_root_id   = fs_info->extent_map_shrinker_last_root;
+               __entry->last_ino       = fs_info->extent_map_shrinker_last_ino;
+       ),
+
+       TP_printk_btrfs("nr_dropped=%ld nr=%ld last_root=%llu(%s) last_ino=%llu",
+                       __entry->nr_dropped, __entry->nr,
+                       show_root_type(__entry->last_root_id), __entry->last_ino)
+);
+
+TRACE_EVENT(btrfs_extent_map_shrinker_remove_em,
+
+       TP_PROTO(const struct btrfs_inode *inode, const struct extent_map *em),
+
+       TP_ARGS(inode, em),
+
+       TP_STRUCT__entry_btrfs(
+               __field(        u64,    ino             )
+               __field(        u64,    root_id         )
+               __field(        u64,    start           )
+               __field(        u64,    len             )
+               __field(        u64,    block_start     )
+               __field(        u32,    flags           )
+       ),
+
+       TP_fast_assign_btrfs(inode->root->fs_info,
+               __entry->ino            = btrfs_ino(inode);
+               __entry->root_id        = inode->root->root_key.objectid;
+               __entry->start          = em->start;
+               __entry->len            = em->len;
+               __entry->block_start    = em->block_start;
+               __entry->flags          = em->flags;
+       ),
+
+       TP_printk_btrfs(
+"ino=%llu root=%llu(%s) start=%llu len=%llu block_start=%llu(%s) flags=%s",
+                       __entry->ino, show_root_type(__entry->root_id),
+                       __entry->start, __entry->len,
+                       show_map_type(__entry->block_start),
+                       show_map_flags(__entry->flags))
+);
+
 #endif /* _TRACE_BTRFS_H */
 
 /* This part must be outside protection */