Re: [PATCH] mm: cma: add trace events for CMA alloc perf testing

[Minchan Kim]

On Wed, Mar 24, 2021 at 06:07:40PM +0200, Georgi Djakov wrote:
> From: Liam Mark <lmark@xxxxxxxxxxxxxx>
> 
> Add cma and migrate trace events to enable CMA allocation
> performance to be measured via ftrace.
> 
> Signed-off-by: Liam Mark <lmark@xxxxxxxxxxxxxx>
> Signed-off-by: Georgi Djakov <georgi.djakov@xxxxxxxxxx>
> ---
>  include/trace/events/cma.h     | 39 +++++++++++++++++++++++++++++++++-
>  include/trace/events/migrate.h | 22 +++++++++++++++++++
>  mm/cma.c                       |  4 ++++
>  mm/migrate.c                   |  2 ++
>  4 files changed, 66 insertions(+), 1 deletion(-)
> 
> diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
> index 5017a8829270..cdfd06afb39a 100644
> --- a/include/trace/events/cma.h
> +++ b/include/trace/events/cma.h
> @@ -8,7 +8,7 @@
>  #include <linux/types.h>
>  #include <linux/tracepoint.h>
>  
> -TRACE_EVENT(cma_alloc,
> +DECLARE_EVENT_CLASS(cma_alloc_class,
>  
>  	TP_PROTO(unsigned long pfn, const struct page *page,
>  		 unsigned int count, unsigned int align),
> @@ -61,6 +61,43 @@ TRACE_EVENT(cma_release,
>  		  __entry->count)
>  );
>  
> +TRACE_EVENT(cma_alloc_start,
> +
> +	TP_PROTO(unsigned int count, unsigned int align),
> +
> +	TP_ARGS(count, align),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned int, count)
> +		__field(unsigned int, align)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->count = count;
> +		__entry->align = align;
> +	),
> +
> +	TP_printk("count=%u align=%u",
> +		  __entry->count,
> +		  __entry->align)
> +);
> +
> +DEFINE_EVENT(cma_alloc_class, cma_alloc,
> +
> +	TP_PROTO(unsigned long pfn, const struct page *page,
> +		 unsigned int count, unsigned int align),
> +
> +	TP_ARGS(pfn, page, count, align)
> +);
> +
> +DEFINE_EVENT(cma_alloc_class, cma_alloc_busy_retry,
> +
> +	TP_PROTO(unsigned long pfn, const struct page *page,
> +		 unsigned int count, unsigned int align),
> +
> +	TP_ARGS(pfn, page, count, align)
> +);
> +
>  #endif /* _TRACE_CMA_H */
>  
>  /* This part must be outside protection */
> diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h
> index 363b54ce104c..9fb2a3bbcdfb 100644
> --- a/include/trace/events/migrate.h
> +++ b/include/trace/events/migrate.h
> @@ -82,6 +82,28 @@ TRACE_EVENT(mm_migrate_pages,
>  		__print_symbolic(__entry->mode, MIGRATE_MODE),
>  		__print_symbolic(__entry->reason, MIGRATE_REASON))
>  );
> +
> +TRACE_EVENT(mm_migrate_pages_start,
> +
> +	TP_PROTO(enum migrate_mode mode, int reason),
> +
> +	TP_ARGS(mode, reason),
> +
> +	TP_STRUCT__entry(
> +		__field(enum migrate_mode, mode)
> +		__field(int, reason)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->mode	= mode;
> +		__entry->reason	= reason;
> +	),
> +
> +	TP_printk("mode=%s reason=%s",
> +		  __print_symbolic(__entry->mode, MIGRATE_MODE),
> +		  __print_symbolic(__entry->reason, MIGRATE_REASON))
> +);
> +
>  #endif /* _TRACE_MIGRATE_H */
>  
>  /* This part must be outside protection */
> diff --git a/mm/cma.c b/mm/cma.c
> index 90e27458ddb7..984c85fd16ec 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -443,6 +443,8 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>  	if (!count)
>  		goto out;
>  
> +	trace_cma_alloc_start(count, align);

Can we add cma->name here to identify what cma instance would be?

> +
>  	mask = cma_bitmap_aligned_mask(cma, align);
>  	offset = cma_bitmap_aligned_offset(cma, align);
>  	bitmap_maxno = cma_bitmap_maxno(cma);
> @@ -483,6 +485,8 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>  
>  		pr_debug("%s(): memory range at %p is busy, retrying\n",
>  			 __func__, pfn_to_page(pfn));
> +
> +		trace_cma_alloc_busy_retry(pfn, pfn_to_page(pfn), count, align);
>  		/* try again with a bit different memory target */
>  		start = bitmap_no + mask + 1;
>  	}
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 47df0df8f21a..58b1b03e0c98 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1445,6 +1445,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
>  	int rc, nr_subpages;
>  	LIST_HEAD(ret_pages);
>  
> +	trace_mm_migrate_pages_start(mode, reason);
> +
>  	if (!swapwrite)
>  		current->flags |= PF_SWAPWRITE;
>  
>