From 854c2f365d7e0b5b1250953e03860f09a7847c39 Mon Sep 17 00:00:00 2001 From: Boris Burkov Date: Thu, 15 Dec 2022 16:06:32 -0800 Subject: btrfs: add more find_free_extent tracepoints find_free_extent is a complicated function. It consists (at least) of: - a hint that jumps into the middle of a for loop macro - a middle loop trying every raid level - an outer loop ascending through ffe loop levels - complicated logic for skipping some of those ffe loop levels - multiple underlying in-bg allocators (zoned, cluster, no cluster) Which is all to say that more tracing is helpful for debugging its behavior. Add two new tracepoints: at the entrance to the block_groups loop (hit for every raid level and every ffe_ctl loop) and at the point we seriously consider a block_group for allocation. This way we can see the whole path through the algorithm, including hints, multiple loops, etc. Reviewed-by: Johannes Thumshirn Signed-off-by: Boris Burkov Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/extent-tree.c | 4 +++ fs/btrfs/extent-tree.h | 3 ++ include/trace/events/btrfs.h | 81 ++++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 85 insertions(+), 3 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index b26cbf6cae8b..203c8cbb9983 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -4261,6 +4261,7 @@ static noinline int find_free_extent(struct btrfs_root *root, block_group->flags); btrfs_lock_block_group(block_group, ffe_ctl->delalloc); + ffe_ctl->hinted = true; goto have_block_group; } } else if (block_group) { @@ -4268,6 +4269,7 @@ static noinline int find_free_extent(struct btrfs_root *root, } } search: + trace_find_free_extent_search_loop(root, ffe_ctl); ffe_ctl->have_caching_bg = false; if (ffe_ctl->index == btrfs_bg_flags_to_raid_index(ffe_ctl->flags) || ffe_ctl->index == 0) @@ -4277,6 +4279,7 @@ search: &space_info->block_groups[ffe_ctl->index], list) { struct btrfs_block_group *bg_ret; + ffe_ctl->hinted = false; /* If the block group is read-only, we can skip it entirely. */ if (unlikely(block_group->ro)) { if (ffe_ctl->for_treelog) @@ -4318,6 +4321,7 @@ search: } have_block_group: + trace_find_free_extent_have_block_group(root, ffe_ctl, block_group); ffe_ctl->cached = btrfs_block_group_done(block_group); if (unlikely(!ffe_ctl->cached)) { ffe_ctl->have_caching_bg = true; diff --git a/fs/btrfs/extent-tree.h b/fs/btrfs/extent-tree.h index 64fa8ad7914a..daa5e3505886 100644 --- a/fs/btrfs/extent-tree.h +++ b/fs/btrfs/extent-tree.h @@ -76,6 +76,9 @@ struct find_free_extent_ctl { /* Allocation policy */ enum btrfs_extent_allocation_policy policy; + + /* Whether or not the allocator is currently following a hint */ + bool hinted; }; enum btrfs_inline_ref_type { diff --git a/include/trace/events/btrfs.h b/include/trace/events/btrfs.h index 8a422e29d064..cc2eaab28d58 100644 --- a/include/trace/events/btrfs.h +++ b/include/trace/events/btrfs.h @@ -1268,6 +1268,77 @@ TRACE_EVENT(find_free_extent, BTRFS_GROUP_FLAGS)) ); +TRACE_EVENT(find_free_extent_search_loop, + + TP_PROTO(const struct btrfs_root *root, + const struct find_free_extent_ctl *ffe_ctl), + + TP_ARGS(root, ffe_ctl), + + TP_STRUCT__entry_btrfs( + __field( u64, root_objectid ) + __field( u64, num_bytes ) + __field( u64, empty_size ) + __field( u64, flags ) + __field( u64, loop ) + ), + + TP_fast_assign_btrfs(root->fs_info, + __entry->root_objectid = root->root_key.objectid; + __entry->num_bytes = ffe_ctl->num_bytes; + __entry->empty_size = ffe_ctl->empty_size; + __entry->flags = ffe_ctl->flags; + __entry->loop = ffe_ctl->loop; + ), + + TP_printk_btrfs("root=%llu(%s) len=%llu empty_size=%llu flags=%llu(%s) loop=%llu", + show_root_type(__entry->root_objectid), + __entry->num_bytes, __entry->empty_size, __entry->flags, + __print_flags((unsigned long)__entry->flags, "|", BTRFS_GROUP_FLAGS), + __entry->loop) +); + +TRACE_EVENT(find_free_extent_have_block_group, + + TP_PROTO(const struct btrfs_root *root, + const struct find_free_extent_ctl *ffe_ctl, + const struct btrfs_block_group *block_group), + + TP_ARGS(root, ffe_ctl, block_group), + + TP_STRUCT__entry_btrfs( + __field( u64, root_objectid ) + __field( u64, num_bytes ) + __field( u64, empty_size ) + __field( u64, flags ) + __field( u64, loop ) + __field( bool, hinted ) + __field( u64, bg_start ) + __field( u64, bg_flags ) + ), + + TP_fast_assign_btrfs(root->fs_info, + __entry->root_objectid = root->root_key.objectid; + __entry->num_bytes = ffe_ctl->num_bytes; + __entry->empty_size = ffe_ctl->empty_size; + __entry->flags = ffe_ctl->flags; + __entry->loop = ffe_ctl->loop; + __entry->hinted = ffe_ctl->hinted; + __entry->bg_start = block_group->start; + __entry->bg_flags = block_group->flags; + ), + + TP_printk_btrfs( +"root=%llu(%s) len=%llu empty_size=%llu flags=%llu(%s) loop=%llu hinted=%d block_group=%llu bg_flags=%llu(%s)", + show_root_type(__entry->root_objectid), + __entry->num_bytes, __entry->empty_size, __entry->flags, + __print_flags((unsigned long)__entry->flags, "|", BTRFS_GROUP_FLAGS), + __entry->loop, __entry->hinted, + __entry->bg_start, __entry->bg_flags, + __print_flags((unsigned long)__entry->bg_flags, "|", + BTRFS_GROUP_FLAGS)) +); + DECLARE_EVENT_CLASS(btrfs__reserve_extent, TP_PROTO(const struct btrfs_block_group *block_group, @@ -1280,6 +1351,8 @@ DECLARE_EVENT_CLASS(btrfs__reserve_extent, __field( u64, flags ) __field( u64, start ) __field( u64, len ) + __field( u64, loop ) + __field( bool, hinted ) ), TP_fast_assign_btrfs(block_group->fs_info, @@ -1287,15 +1360,17 @@ DECLARE_EVENT_CLASS(btrfs__reserve_extent, __entry->flags = block_group->flags; __entry->start = ffe_ctl->search_start; __entry->len = ffe_ctl->num_bytes; + __entry->loop = ffe_ctl->loop; + __entry->hinted = ffe_ctl->hinted; ), - TP_printk_btrfs("root=%llu(%s) block_group=%llu flags=%llu(%s) " - "start=%llu len=%llu", + TP_printk_btrfs( +"root=%llu(%s) block_group=%llu flags=%llu(%s) start=%llu len=%llu loop=%llu hinted=%d", show_root_type(BTRFS_EXTENT_TREE_OBJECTID), __entry->bg_objectid, __entry->flags, __print_flags((unsigned long)__entry->flags, "|", BTRFS_GROUP_FLAGS), - __entry->start, __entry->len) + __entry->start, __entry->len, __entry->loop, __entry->hinted) ); DEFINE_EVENT(btrfs__reserve_extent, btrfs_reserve_extent, -- cgit v1.2.3