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Message-ID: <2bbbd69e-0804-4f9c-8aca-572032eeedf8@redhat.com>
Date:   Tue, 12 Dec 2023 14:45:40 +0100
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Subject: Re: [PATCH v3 3/4] mm/ksm: add tracepoint for ksm advisor
Content-Language: en-US
To:     Stefan Roesch <shr@devkernel.io>, kernel-team@fb.com
Cc:     akpm@linux-foundation.org, hannes@cmpxchg.org, riel@surriel.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
References: <20231204234906.1237478-1-shr@devkernel.io>
 <20231204234906.1237478-4-shr@devkernel.io>
From:   David Hildenbrand <david@redhat.com>
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Organization: Red Hat
In-Reply-To: <20231204234906.1237478-4-shr@devkernel.io>
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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