Patch looks good to me. But CC more people for review.
On Fri, Jan 11, 2013 at 01:06:37PM -0800, Tejun Heo wrote:
> Add tracepoints for page dirtying, writeback_single_inode start, inode
> dirtying and writeback. For the latter two inode events, a pair of
> events are defined to denote start and end of the operations (the
> starting one has _start suffix and the one w/o suffix happens after
> the operation is complete). These inode ops are FS specific and can
> be non-trivial and having enclosing tracepoints is useful for external
> tracers.
>
> This is part of tracepoint additions to improve visiblity into
> dirtying / writeback operations for io tracer and userland.
>
> v2: writeback_dirty_inode[_start] TPs may be called for files on
> pseudo FSes w/ unregistered bdi. Check whether bdi->dev is %NULL
> before dereferencing.
>
> v3: buffer dirtying moved to a block TP.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> ---
> fs/fs-writeback.c | 16 +++++-
> include/trace/events/writeback.h | 116 +++++++++++++++++++++++++++++++++++++++
> mm/page-writeback.c | 2 +
> 3 files changed, 132 insertions(+), 2 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 310972b..359494e 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -318,8 +318,14 @@ static void queue_io(struct bdi_writeback *wb, struct wb_writeback_work *work)
>
> static int write_inode(struct inode *inode, struct writeback_control *wbc)
> {
> - if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode))
> - return inode->i_sb->s_op->write_inode(inode, wbc);
> + int ret;
> +
> + if (inode->i_sb->s_op->write_inode && !is_bad_inode(inode)) {
> + trace_writeback_write_inode_start(inode, wbc);
> + ret = inode->i_sb->s_op->write_inode(inode, wbc);
> + trace_writeback_write_inode(inode, wbc);
> + return ret;
> + }
> return 0;
> }
>
> @@ -450,6 +456,8 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
>
> WARN_ON(!(inode->i_state & I_SYNC));
>
> + trace_writeback_single_inode_start(inode, wbc, nr_to_write);
> +
> ret = do_writepages(mapping, wbc);
>
> /*
> @@ -1150,8 +1158,12 @@ void __mark_inode_dirty(struct inode *inode, int flags)
> * dirty the inode itself
> */
> if (flags & (I_DIRTY_SYNC | I_DIRTY_DATASYNC)) {
> + trace_writeback_dirty_inode_start(inode, flags);
> +
> if (sb->s_op->dirty_inode)
> sb->s_op->dirty_inode(inode, flags);
> +
> + trace_writeback_dirty_inode(inode, flags);
> }
>
> /*
> diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
> index b453d92..6a16fd2 100644
> --- a/include/trace/events/writeback.h
> +++ b/include/trace/events/writeback.h
> @@ -32,6 +32,115 @@
>
> struct wb_writeback_work;
>
> +TRACE_EVENT(writeback_dirty_page,
> +
> + TP_PROTO(struct page *page, struct address_space *mapping),
> +
> + TP_ARGS(page, mapping),
> +
> + TP_STRUCT__entry (
> + __array(char, name, 32)
> + __field(unsigned long, ino)
> + __field(pgoff_t, index)
> + ),
> +
> + TP_fast_assign(
> + strncpy(__entry->name,
> + mapping ? dev_name(mapping->backing_dev_info->dev) : "(unknown)", 32);
> + __entry->ino = mapping ? mapping->host->i_ino : 0;
> + __entry->index = page->index;
> + ),
> +
> + TP_printk("bdi %s: ino=%lu index=%lu",
> + __entry->name,
> + __entry->ino,
> + __entry->index
> + )
> +);
> +
> +DECLARE_EVENT_CLASS(writeback_dirty_inode_template,
> +
> + TP_PROTO(struct inode *inode, int flags),
> +
> + TP_ARGS(inode, flags),
> +
> + TP_STRUCT__entry (
> + __array(char, name, 32)
> + __field(unsigned long, ino)
> + __field(unsigned long, flags)
> + ),
> +
> + TP_fast_assign(
> + struct backing_dev_info *bdi = inode->i_mapping->backing_dev_info;
> +
> + /* may be called for files on pseudo FSes w/ unregistered bdi */
> + strncpy(__entry->name,
> + bdi->dev ? dev_name(bdi->dev) : "(unknown)", 32);
> + __entry->ino = inode->i_ino;
> + __entry->flags = flags;
> + ),
> +
> + TP_printk("bdi %s: ino=%lu flags=%s",
> + __entry->name,
> + __entry->ino,
> + show_inode_state(__entry->flags)
> + )
> +);
> +
> +DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode_start,
> +
> + TP_PROTO(struct inode *inode, int flags),
> +
> + TP_ARGS(inode, flags)
> +);
> +
> +DEFINE_EVENT(writeback_dirty_inode_template, writeback_dirty_inode,
> +
> + TP_PROTO(struct inode *inode, int flags),
> +
> + TP_ARGS(inode, flags)
> +);
> +
> +DECLARE_EVENT_CLASS(writeback_write_inode_template,
> +
> + TP_PROTO(struct inode *inode, struct writeback_control *wbc),
> +
> + TP_ARGS(inode, wbc),
> +
> + TP_STRUCT__entry (
> + __array(char, name, 32)
> + __field(unsigned long, ino)
> + __field(int, sync_mode)
> + ),
> +
> + TP_fast_assign(
> + strncpy(__entry->name,
> + dev_name(inode->i_mapping->backing_dev_info->dev), 32);
> + __entry->ino = inode->i_ino;
> + __entry->sync_mode = wbc->sync_mode;
> + ),
> +
> + TP_printk("bdi %s: ino=%lu sync_mode=%d",
> + __entry->name,
> + __entry->ino,
> + __entry->sync_mode
> + )
> +);
> +
> +DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode_start,
> +
> + TP_PROTO(struct inode *inode, struct writeback_control *wbc),
> +
> + TP_ARGS(inode, wbc)
> +);
> +
> +DEFINE_EVENT(writeback_write_inode_template, writeback_write_inode,
> +
> + TP_PROTO(struct inode *inode, struct writeback_control *wbc),
> +
> + TP_ARGS(inode, wbc)
> +);
> +
> DECLARE_EVENT_CLASS(writeback_work_class,
> TP_PROTO(struct backing_dev_info *bdi, struct wb_writeback_work *work),
> TP_ARGS(bdi, work),
> @@ -479,6 +588,13 @@ DECLARE_EVENT_CLASS(writeback_single_inode_template,
> )
> );
>
> +DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode_start,
> + TP_PROTO(struct inode *inode,
> + struct writeback_control *wbc,
> + unsigned long nr_to_write),
> + TP_ARGS(inode, wbc, nr_to_write)
> +);
> +
> DEFINE_EVENT(writeback_single_inode_template, writeback_single_inode,
> TP_PROTO(struct inode *inode,
> struct writeback_control *wbc,
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 0713bfb..3734cef 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -1982,6 +1982,8 @@ int __set_page_dirty_no_writeback(struct page *page)
> */
> void account_page_dirtied(struct page *page, struct address_space *mapping)
> {
> + trace_writeback_dirty_page(page, mapping);
> +
> if (mapping_cap_account_dirty(mapping)) {
> __inc_zone_page_state(page, NR_FILE_DIRTY);
> __inc_zone_page_state(page, NR_DIRTIED);
> --
> 1.8.0.2
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