Re: + mm-damon-add-age-of-region-tracepoint-support.patch added to -mm tree

[SeongJae Park <sj@kernel.org>]

On Mon, 15 Nov 2021 09:48:33 -0800 akpm@linux-foundation.org wrote:

> 
> The patch titled
>      Subject: mm/damon: add 'age' of region tracepoint support
> has been added to the -mm tree.  Its filename is
>      mm-damon-add-age-of-region-tracepoint-support.patch
> 
> This patch should soon appear at
>     https://ozlabs.org/~akpm/mmots/broken-out/mm-damon-add-age-of-region-tracepoint-support.patch
> and later at
>     https://ozlabs.org/~akpm/mmotm/broken-out/mm-damon-add-age-of-region-tracepoint-support.patch
> 
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> 
> *** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
> 
> The -mm tree is included into linux-next and is updated
> there every 3-4 working days
> 
> ------------------------------------------------------
> From: Xin Hao <xhao@linux.alibaba.com>
> Subject: mm/damon: add 'age' of region tracepoint support
> 
> In Damon, we can get age information by analyzing the nr_access change,
> But short time sampling is not effective, we have to obtain enough data
> for analysis through long time trace, this also means that we need to
> consume more cpu resources and storage space.
> 
> Now the region add a new 'age' variable, we only need to get the change of
> age value through a little time trace, for example, age has been
> increasing to 141, but nr_access shows a value of 0 at the same time,
> Through this，we can conclude that the region has a very low nr_access
> value for a long time.
> 
> Link: https://lkml.kernel.org/r/b9def1262af95e0dc1d0caea447886434db01161.1636989871.git.xhao@linux.alibaba.com
> Fixes: 2fcb93629ad8 ("mm/damon: add a tracepoint")

This is not true, as 'age' information was not invented at that time.

Other than this,

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

> Signed-off-by: Xin Hao <xhao@linux.alibaba.com>
> Cc: Muchun Song <songmuchun@bytedance.com>
> Cc: SeongJae Park <sj@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  include/trace/events/damon.h |    7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> --- a/include/trace/events/damon.h~mm-damon-add-age-of-region-tracepoint-support
> +++ a/include/trace/events/damon.h
> @@ -22,6 +22,7 @@ TRACE_EVENT(damon_aggregated,
>  		__field(unsigned long, start)
>  		__field(unsigned long, end)
>  		__field(unsigned int, nr_accesses)
> +		__field(unsigned int, age)
>  	),
>  
>  	TP_fast_assign(
> @@ -30,11 +31,13 @@ TRACE_EVENT(damon_aggregated,
>  		__entry->start = r->ar.start;
>  		__entry->end = r->ar.end;
>  		__entry->nr_accesses = r->nr_accesses;
> +		__entry->age = r->age;
>  	),
>  
> -	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
> +	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u %u",
>  			__entry->target_id, __entry->nr_regions,
> -			__entry->start, __entry->end, __entry->nr_accesses)
> +			__entry->start, __entry->end,
> +			__entry->nr_accesses, __entry->age)
>  );
>  
>  #endif /* _TRACE_DAMON_H */
> _
> 
> Patches currently in -mm which might be from xhao@linux.alibaba.com are
> 
> mm-damon-unified-access_check-function-naming-rules.patch
> mm-damon-add-age-of-region-tracepoint-support.patch
> mm-damon-core-using-function-abs-instead-of-diff_of.patch
> mm-damon-remove-some-no-need-func-definitions-in-damonh-file.patch