linux-kernel - Re: [PATCH v2] mm: add alloc_contig_migrate

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Date: Wed, 28 Feb 2024 09:47:03 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: Richard Chang <richardycc@...gle.com>
Cc: mhiramat@...nel.org, mathieu.desnoyers@...icios.com,
 akpm@...ux-foundation.org, liumartin@...gle.com, surenb@...gle.com,
 minchan@...nel.org, linux-kernel@...r.kernel.org,
 linux-trace-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH v2] mm: add alloc_contig_migrate_range allocation
 statistics

On Wed, 28 Feb 2024 05:11:17 +0000
Richard Chang <richardycc@...gle.com> wrote:

> alloc_contig_migrate_range has every information to be able to
> understand big contiguous allocation latency. For example, how many
> pages are migrated, how many times they were needed to unmap from
> page tables.
> 
> This patch adds the trace event to collect the allocation statistics.
> In the field, it was quite useful to understand CMA allocation
> latency.
> 
> Signed-off-by: Richard Chang <richardycc@...gle.com>
> ---
> * from v1 - https://lore.kernel.org/linux-mm/20240226100045.2083962-1-richardycc@google.com/
>   * Move the trace event int field to the end of the longs - rostedt
>   * Do the calculation only when tracing is enabled - rostedt
> 
>  include/trace/events/kmem.h | 38 +++++++++++++++++++++++++++++++++++++
>  mm/internal.h               |  3 ++-
>  mm/page_alloc.c             | 32 ++++++++++++++++++++++++++-----
>  mm/page_isolation.c         |  2 +-
>  4 files changed, 68 insertions(+), 7 deletions(-)
> 
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index 58688768ef0f..6e62cc64cd92 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -304,6 +304,44 @@ TRACE_EVENT(mm_page_alloc_extfrag,
>  		__entry->change_ownership)
>  );
>  
> +TRACE_EVENT(mm_alloc_contig_migrate_range_info,
> +
> +	TP_PROTO(unsigned long start,
> +		 unsigned long end,
> +		 unsigned long nr_migrated,
> +		 unsigned long nr_reclaimed,
> +		 unsigned long nr_mapped,
> +		 int migratetype),

Well, you didn't need to change the order of the parameters.

Anyway, from a tracing point of view:

Reviewed-by: Steven Rostedt (Google) <rostedt@...dmis.org.

-- Steve

> +
> +	TP_ARGS(start, end, nr_migrated, nr_reclaimed, nr_mapped, migratetype),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, start)
> +		__field(unsigned long, end)
> +		__field(unsigned long, nr_migrated)
> +		__field(unsigned long, nr_reclaimed)
> +		__field(unsigned long, nr_mapped)
> +		__field(int, migratetype)
> +	),
> +