[Devel] [PATCH rh7 v2] mm/page_alloc: add latency to the page_alloc tracepoint

[Kirill Gorkunov]

On Mon, Dec 17, 2018 at 01:04:10PM +0300, Andrey Ryabinin wrote:
> Add 'lat' field to the mm_page_alloc tracepoint. It shows allocation
> latency in microseconds (0.000001 second).
... 
>  
>  	TP_STRUCT__entry(
>  		__field(	struct page *,	page		)
>  		__field(	unsigned int,	order		)
>  		__field(	gfp_t,		gfp_flags	)
>  		__field(	int,		migratetype	)
> +		__field(	u64,		time		)
>  	),
...
> -	trace_mm_page_alloc(page, order, gfp_mask, migratetype);
> +	trace_mm_page_alloc(page, order, gfp_mask, migratetype,
> +			jiffies_to_usecs(jiffies - start));

jiffies_to_usecs provides u32 result, why do you need u64 here?