linux-kernel - Re: [PATCH] writeback: expose cgroup info in trace_writeback_pages

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Date:   Tue, 19 Mar 2019 11:40:30 +0100
From:   Jan Kara <jack@...e.cz>
To:     Yafang Shao <laoar.shao@...il.com>
Cc:     viro@...iv.linux.org.uk, tj@...nel.org, rostedt@...dmis.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] writeback: expose cgroup info in
 trace_writeback_pages_written()

On Sat 23-02-19 21:35:49, Yafang Shao wrote:
> With cgroup v2 writeback, we can know these pages are written from which
> cgroup.
> So expose the cgroup_ino for better tracking.
> 
> Signed-off-by: Yafang Shao <laoar.shao@...il.com>

Fine by me. You can add:

Acked-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/fs-writeback.c                | 4 ++--
>  include/trace/events/writeback.h | 9 ++++++---
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 36855c1..e98a33e 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -1973,7 +1973,7 @@ void wb_workfn(struct work_struct *work)
>  		 */
>  		do {
>  			pages_written = wb_do_writeback(wb);
> -			trace_writeback_pages_written(pages_written);
> +			trace_writeback_pages_written(wb, pages_written);
>  		} while (!list_empty(&wb->work_list));
>  	} else {
>  		/*
> @@ -1983,7 +1983,7 @@ void wb_workfn(struct work_struct *work)
>  		 */
>  		pages_written = writeback_inodes_wb(wb, 1024,
>  						    WB_REASON_FORKER_THREAD);
> -		trace_writeback_pages_written(pages_written);
> +		trace_writeback_pages_written(wb, pages_written);
>  	}
>  
>  	if (!list_empty(&wb->work_list))
> diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h
> index 32db72c..a806713 100644
> --- a/include/trace/events/writeback.h
> +++ b/include/trace/events/writeback.h
> @@ -255,15 +255,18 @@ static inline unsigned int __trace_wbc_assign_cgroup(struct writeback_control *w
>  DEFINE_WRITEBACK_WORK_EVENT(writeback_wait);
>  
>  TRACE_EVENT(writeback_pages_written,
> -	TP_PROTO(long pages_written),
> -	TP_ARGS(pages_written),
> +	TP_PROTO(struct bdi_writeback *wb, long pages_written),
> +	TP_ARGS(wb, pages_written),
>  	TP_STRUCT__entry(
>  		__field(long,		pages)
> +		__field(unsigned int,	cgroup_ino)
>  	),
>  	TP_fast_assign(
>  		__entry->pages		= pages_written;
> +		__entry->cgroup_ino	= __trace_wb_assign_cgroup(wb);
>  	),
> -	TP_printk("%ld", __entry->pages)
> +	TP_printk("pages=%ld cgroup_ino=%u",
> +		   __entry->pages, __entry->cgroup_ino)
>  );
>  
>  DECLARE_EVENT_CLASS(writeback_class,
> -- 
> 1.8.3.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR