Re: [RFC PATCH V3 14/17] trace/kscand: Add tracing of scanning and migration

[Jonathan Cameron]

On Thu, 14 Aug 2025 15:33:04 +0000
Raghavendra K T <raghavendra.kt@xxxxxxx> wrote:

> Add tracing support to track
>  - start and end of scanning.
>  - migration.
> 
> CC: Steven Rostedt <rostedt@xxxxxxxxxxx>
> CC: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> CC: linux-trace-kernel@xxxxxxxxxxxxxxx
> 
CC s are part of tags block so no blank line.

Probably move them under the --- as I doubt we need to keep these
in the git log long term.

> Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxx>
> ---
>  include/trace/events/kmem.h | 99 +++++++++++++++++++++++++++++++++++++
>  mm/kscand.c                 |  9 ++++
>  2 files changed, 108 insertions(+)
> 
> diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
> index f74925a6cf69..d6e544b067b9 100644
> --- a/include/trace/events/kmem.h
> +++ b/include/trace/events/kmem.h
> @@ -9,6 +9,105 @@
>  #include <linux/tracepoint.h>
>  #include <trace/events/mmflags.h>
>  
> +#ifdef CONFIG_KSCAND
> +DECLARE_EVENT_CLASS(kmem_mm_class,
> +
> +	TP_PROTO(struct mm_struct *mm),
> +
> +	TP_ARGS(mm),
> +
> +	TP_STRUCT__entry(
> +		__field(	struct mm_struct *, mm		)

Trace header formatting is sometimes interesting. But I have no
idea why you have this padded like that.

> +	),
> +
> +	TP_fast_assign(
> +		__entry->mm = mm;
> +	),
> +
> +	TP_printk("mm = %p", __entry->mm)
> +);
> +
> +DEFINE_EVENT(kmem_mm_class, kmem_mm_enter,
> +	TP_PROTO(struct mm_struct *mm),
> +	TP_ARGS(mm)
> +);
> +
> +DEFINE_EVENT(kmem_mm_class, kmem_mm_exit,
> +	TP_PROTO(struct mm_struct *mm),
> +	TP_ARGS(mm)
> +);
> +
> +DEFINE_EVENT(kmem_mm_class, kmem_scan_mm_start,
> +	TP_PROTO(struct mm_struct *mm),
> +	TP_ARGS(mm)
> +);
> +
> +TRACE_EVENT(kmem_scan_mm_end,
> +
> +	TP_PROTO( struct mm_struct *mm,
> +		 unsigned long start,
> +		 unsigned long total,
> +		 unsigned long scan_period,
> +		 unsigned long scan_size,
> +		 int target_node),
> +
> +	TP_ARGS(mm, start, total, scan_period, scan_size, target_node),
> +
> +	TP_STRUCT__entry(
> +		__field(	struct mm_struct *, mm		)
> +		__field(	unsigned long,   start		)
> +		__field(	unsigned long,   total		)
> +		__field(	unsigned long,   scan_period	)
> +		__field(	unsigned long,   scan_size	)
> +		__field(	int,		 target_node	)

Similar. Aligning stuff might make sense but why the spacing before the type?