Re: [PATCH] mm: page_alloc: add nid to mm_page_alloc tracepoint

["Vlastimil Babka (SUSE)" <vbabka@kernel.org>]

On 11/13/26 07:20, Ye Bin wrote:
> From: Ye Bin <yebin10@huawei.com>
> 
> Add the NUMA node id to the mm_page_alloc trace event so that page
> allocations can be attributed to a specific node directly from the
> trace, without having to look up the pfn separately.

But is it the right tradeoff? Trace data should be as minimal as possible
for cpu and memory purposes. Anything extra that can be achieved by
postprocessing is better done that way. Matching pfn to node using
/proc/zoneinfo is simple.

> The nid is derived from the allocated page, or set to -1 when no page
> is available (e.g. failed allocations).
> 
> Signed-off-by: Ye Bin <yebin10@huawei.com>
> ---
>  include/trace/events/kmem.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index cd7920c81f85..8bf4e992d8bb 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -189,6 +189,7 @@ TRACE_EVENT(mm_page_alloc,
>  		__field(	unsigned int,	order		)
>  		__field(	unsigned long,	gfp_flags	)
>  		__field(	int,		migratetype	)
> +		__field(	int,		nid		)
>  	),
>  
>  	TP_fast_assign(
> @@ -196,13 +197,15 @@ TRACE_EVENT(mm_page_alloc,
>  		__entry->order		= order;
>  		__entry->gfp_flags	= (__force unsigned long)gfp_flags;
>  		__entry->migratetype	= migratetype;
> +		__entry->nid		= page ? page_to_nid(page) : -1;
>  	),
>  
> -	TP_printk("page=%p pfn=0x%lx order=%d migratetype=%d gfp_flags=%s",
> +	TP_printk("page=%p pfn=0x%lx order=%d migratetype=%d nid=%d gfp_flags=%s",
>  		__entry->pfn != -1UL ? pfn_to_page(__entry->pfn) : NULL,
>  		__entry->pfn != -1UL ? __entry->pfn : 0,
>  		__entry->order,
>  		__entry->migratetype,
> +		__entry->nid,
>  		show_gfp_flags(__entry->gfp_flags))
>  );
>