Re: [PATCH 4/7] mm, vmscan: show LRU name in mm_vmscan_lru_isolate tracepoint

[Vlastimil Babka <vbabka@suse.cz>]

On 12/28/2016 04:30 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> mm_vmscan_lru_isolate currently prints only whether the LRU we isolate
> from is file or anonymous but we do not know which LRU this is. It is
> useful to know whether the list is file or anonymous as well. Change
> the tracepoint to show symbolic names of the lru rather.
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  include/trace/events/vmscan.h | 20 ++++++++++++++------
>  mm/vmscan.c                   |  2 +-
>  2 files changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/include/trace/events/vmscan.h b/include/trace/events/vmscan.h
> index 6af4dae46db2..cc0b4c456c78 100644
> --- a/include/trace/events/vmscan.h
> +++ b/include/trace/events/vmscan.h
> @@ -36,6 +36,14 @@
>  		(RECLAIM_WB_ASYNC) \
>  	)
>
> +#define show_lru_name(lru) \
> +	__print_symbolic(lru, \
> +			{LRU_INACTIVE_ANON, "LRU_INACTIVE_ANON"}, \
> +			{LRU_ACTIVE_ANON, "LRU_ACTIVE_ANON"}, \
> +			{LRU_INACTIVE_FILE, "LRU_INACTIVE_FILE"}, \
> +			{LRU_ACTIVE_FILE, "LRU_ACTIVE_FILE"}, \
> +			{LRU_UNEVICTABLE, "LRU_UNEVICTABLE"})
> +

Does this work with external tools such as trace-cmd, i.e. does it export the 
correct format file? I wouldn't expect it to be that easy to avoid the 
EM()/EMe() dance :)

Also can we make the symbolic names lower_case and without the LRU_ prefix? I 
think it's more consistent with other mm tracepoints, shorter and nicer.

>  TRACE_EVENT(mm_vmscan_kswapd_sleep,
>
>  	TP_PROTO(int nid),
> @@ -277,9 +285,9 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
>  		unsigned long nr_skipped,
>  		unsigned long nr_taken,
>  		isolate_mode_t isolate_mode,
> -		int file),
> +		int lru),
>
> -	TP_ARGS(classzone_idx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, file),
> +	TP_ARGS(classzone_idx, order, nr_requested, nr_scanned, nr_skipped, nr_taken, isolate_mode, lru),
>
>  	TP_STRUCT__entry(
>  		__field(int, classzone_idx)
> @@ -289,7 +297,7 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
>  		__field(unsigned long, nr_skipped)
>  		__field(unsigned long, nr_taken)
>  		__field(isolate_mode_t, isolate_mode)
> -		__field(int, file)
> +		__field(int, lru)
>  	),
>
>  	TP_fast_assign(
> @@ -300,10 +308,10 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
>  		__entry->nr_skipped = nr_skipped;
>  		__entry->nr_taken = nr_taken;
>  		__entry->isolate_mode = isolate_mode;
> -		__entry->file = file;
> +		__entry->lru = lru;
>  	),
>
> -	TP_printk("isolate_mode=%d classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu file=%d",
> +	TP_printk("isolate_mode=%d classzone=%d order=%d nr_requested=%lu nr_scanned=%lu nr_skipped=%lu nr_taken=%lu lru=%s",
>  		__entry->isolate_mode,
>  		__entry->classzone_idx,
>  		__entry->order,
> @@ -311,7 +319,7 @@ TRACE_EVENT(mm_vmscan_lru_isolate,
>  		__entry->nr_scanned,
>  		__entry->nr_skipped,
>  		__entry->nr_taken,
> -		__entry->file)
> +		show_lru_name(__entry->lru))
>  );
>
>  TRACE_EVENT(mm_vmscan_writepage,
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 4f7c0d66d629..3f0774f30a42 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1500,7 +1500,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>  	}
>  	*nr_scanned = scan + total_skipped;
>  	trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan,
> -				    skipped, nr_taken, mode, is_file_lru(lru));
> +				    skipped, nr_taken, mode, lru);
>  	update_lru_sizes(lruvec, lru, nr_zone_taken, nr_taken);
>  	return nr_taken;
>  }
>