Re: [PATCH v3 3/4] mm/ksm: add tracepoint for ksm advisor

David Hildenbrand
2023-12-12T13:45:54Z

On 05.12.23 00:49, Stefan Roesch wrote:
> This adds a new tracepoint for the ksm advisor. It reports the last scan
> time, the new setting of the pages_to_scan parameter and the average cpu
> percent usage of the ksmd background thread for the last scan.
>
> Signed-off-by: Stefan Roesch <shr@devkernel.io>
> ---
> include/trace/events/ksm.h | 33 +++++++++++++++++++++++++++++++++
> mm/ksm.c | 1 +
> 2 files changed, 34 insertions(+)
>
> diff --git a/include/trace/events/ksm.h b/include/trace/events/ksm.h
> index b5ac35c1d0e88..e728647b5d268 100644
> --- a/include/trace/events/ksm.h
> +++ b/include/trace/events/ksm.h
> @@ -245,6 +245,39 @@ TRACE_EVENT(ksm_remove_rmap_item,
> __entry->pfn, __entry->rmap_item, __entry->mm)
> );
>
> +/**
> + * ksm_advisor - called after the advisor has run
> + *
> + * @scan_time: scan time in seconds
> + * @pages_to_scan: new pages_to_scan value
> + * @cpu_percent: cpu usage in percent
> + *
> + * Allows to trace the ksm advisor.
> + */
> +TRACE_EVENT(ksm_advisor,
> +
> + TP_PROTO(s64 scan_time, unsigned long pages_to_scan,
> + unsigned int cpu_percent),
> +
> + TP_ARGS(scan_time, pages_to_scan, cpu_percent),
> +
> + TP_STRUCT__entry(
> + __field(s64, scan_time)
> + __field(unsigned long, pages_to_scan)
> + __field(unsigned int, cpu_percent)
> + ),
> +
> + TP_fast_assign(
> + __entry->scan_time = scan_time;
> + __entry->pages_to_scan = pages_to_scan;
> + __entry->cpu_percent = cpu_percent;
> + ),
> +
> + TP_printk("ksm scan time %lld pages_to_scan %lu cpu percent %u",
> + __entry->scan_time, __entry->pages_to_scan,
> + __entry->cpu_percent)
> +);
> +
> #endif /* _TRACE_KSM_H */
>
> /* This part must be outside protection */
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 18b7185bbc65b..b8065c5d5f833 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -455,6 +455,7 @@ static void scan_time_advisor(void)
> advisor_ctx.cpu_time = cpu_time;
>
> ksm_thread_pages_to_scan = pages;
> + trace_ksm_advisor(scan_time, pages, cpu_percent);
> }
>
> static void run_advisor(void)

Acked-by: David Hildenbrand <david@redhat.com>

--
Cheers,

David / dhildenb