Add trace_inode_switch_wbs_queue tracepoint to allow insight into how
many inodes are queued to switch their bdi_writeback structure.
Signed-off-by: Jan Kara <jack@xxxxxxx>
---
fs/fs-writeback.c | 4 ++++
include/trace/events/writeback.h | 29 +++++++++++++++++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7765c3deccd6..094b78ce6d72 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -658,6 +658,8 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
if (!isw->new_wb)
goto out_free;
+ trace_inode_switch_wbs_queue(inode->i_wb, isw->new_wb, 1);
+
if (!inode_prepare_wbs_switch(inode, isw->new_wb))
goto out_free;
@@ -752,6 +754,8 @@ bool cleanup_offline_cgwb(struct bdi_writeback *wb)
return restart;
}
+ trace_inode_switch_wbs_queue(wb, isw->new_wb, nr);
+
/*
* In addition to synchronizing among switchers, I_WB_SWITCH tells
* the RCU protected stat update paths to grab the i_page
diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
index 1e23919c0da9..c08aff044e80 100644
--- a/include/trace/events/writeback.h
+++ b/include/trace/events/writeback.h
@@ -213,6 +213,35 @@ TRACE_EVENT(inode_foreign_history,
)
);
+TRACE_EVENT(inode_switch_wbs_queue,
+
+ TP_PROTO(struct bdi_writeback *old_wb, struct bdi_writeback *new_wb,
+ unsigned int count),
+
+ TP_ARGS(old_wb, new_wb, count),
+
+ TP_STRUCT__entry(
+ __array(char, name, 32)
+ __field(ino_t, old_cgroup_ino)
+ __field(ino_t, new_cgroup_ino)
+ __field(unsigned int, count)
+ ),
+
+ TP_fast_assign(
+ strscpy_pad(__entry->name, bdi_dev_name(old_wb->bdi), 32);
+ __entry->old_cgroup_ino = __trace_wb_assign_cgroup(old_wb);
+ __entry->new_cgroup_ino = __trace_wb_assign_cgroup(new_wb);
+ __entry->count = count;
+ ),
+
+ TP_printk("bdi %s: old_cgroup_ino=%lu new_cgroup_ino=%lu count=%u",
+ __entry->name,
+ (unsigned long)__entry->old_cgroup_ino,
+ (unsigned long)__entry->new_cgroup_ino,
+ __entry->count
+ )
+);
+
TRACE_EVENT(inode_switch_wbs,
TP_PROTO(struct inode *inode, struct bdi_writeback *old_wb,
--
2.51.0
