Note that it adds a little overheads to account the moved/enqueued inodes from b_dirty to b_io. The "moved" accounting may be later used to limit the number of inodes that can be moved in one shot, in order to keep spinlock hold time under control. Signed-off-by: Wu Fengguang --- fs/fs-writeback.c | 14 ++++++++++---- include/trace/events/writeback.h | 25 +++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 4 deletions(-) --- linux-next.orig/fs/fs-writeback.c 2011-05-05 23:53:33.000000000 +0800 +++ linux-next/fs/fs-writeback.c 2011-05-05 23:53:34.000000000 +0800 @@ -258,15 +258,16 @@ static bool inode_dirtied_after(struct i /* * Move expired dirty inodes from @delaying_queue to @dispatch_queue. */ -static void move_expired_inodes(struct list_head *delaying_queue, +static int move_expired_inodes(struct list_head *delaying_queue, struct list_head *dispatch_queue, - unsigned long *older_than_this) + unsigned long *older_than_this) { LIST_HEAD(tmp); struct list_head *pos, *node; struct super_block *sb = NULL; struct inode *inode; int do_sb_sort = 0; + int moved = 0; while (!list_empty(delaying_queue)) { inode = wb_inode(delaying_queue->prev); @@ -277,12 +278,13 @@ static void move_expired_inodes(struct l do_sb_sort = 1; sb = inode->i_sb; list_move(&inode->i_wb_list, &tmp); + moved++; } /* just one sb in list, splice to dispatch_queue and we're done */ if (!do_sb_sort) { list_splice(&tmp, dispatch_queue); - return; + goto out; } /* Move inodes from one superblock together */ @@ -294,6 +296,8 @@ static void move_expired_inodes(struct l list_move(&inode->i_wb_list, dispatch_queue); } } +out: + return moved; } /* @@ -309,9 +313,11 @@ static void move_expired_inodes(struct l */ static void queue_io(struct bdi_writeback *wb, unsigned long *older_than_this) { + int moved; assert_spin_locked(&wb->list_lock); list_splice_init(&wb->b_more_io, &wb->b_io); - move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); + moved = move_expired_inodes(&wb->b_dirty, &wb->b_io, older_than_this); + trace_writeback_queue_io(wb, older_than_this, moved); } static int write_inode(struct inode *inode, struct writeback_control *wbc) --- linux-next.orig/include/trace/events/writeback.h 2011-05-05 23:53:33.000000000 +0800 +++ linux-next/include/trace/events/writeback.h 2011-05-06 00:14:09.000000000 +0800 @@ -158,6 +158,31 @@ DEFINE_WBC_EVENT(wbc_balance_dirty_writt DEFINE_WBC_EVENT(wbc_balance_dirty_wait); DEFINE_WBC_EVENT(wbc_writepage); +TRACE_EVENT(writeback_queue_io, + TP_PROTO(struct bdi_writeback *wb, + unsigned long *older_than_this, + int moved), + TP_ARGS(wb, older_than_this, moved), + TP_STRUCT__entry( + __array(char, name, 32) + __field(unsigned long, older) + __field(long, age) + __field(int, moved) + ), + TP_fast_assign( + strncpy(__entry->name, dev_name(wb->bdi->dev), 32); + __entry->older = older_than_this ? *older_than_this : 0; + __entry->age = older_than_this ? + (jiffies - *older_than_this) * 1000 / HZ : -1; + __entry->moved = moved; + ), + TP_printk("bdi %s: older=%lu age=%ld enqueue=%d", + __entry->name, + __entry->older, /* older_than_this in jiffies */ + __entry->age, /* older_than_this in relative milliseconds */ + __entry->moved) +); + DECLARE_EVENT_CLASS(writeback_congest_waited_template, TP_PROTO(unsigned int usec_timeout, unsigned int usec_delayed), -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/