linux-kernel - Re: [PATCH] Revert "perf: Add a counter for number of user access events in context"

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Message-ID: <20240806114152.GW37996@noisy.programming.kicks-ass.net>
Date: Tue, 6 Aug 2024 13:41:52 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Song Liu <song@...nel.org>
Cc: linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
	Thomas Gleixner <tglx@...utronix.de>, Rob Herring <robh@...nel.org>,
	Will Deacon <will@...nel.org>, Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] Revert "perf: Add a counter for number of user access
 events in context"

On Mon, Aug 05, 2024 at 04:10:31PM -0700, Song Liu wrote:
> This reverts commit 82ff0c022d19c2ad69a472692bb7ee01ac07a40b.
> 
> perf_event->nr_user is not used any more. Remove it.

Might be helpful to know where the user went..

> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Will Deacon <will@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Signed-off-by: Song Liu <song@...nel.org>
> ---
>  include/linux/perf_event.h | 1 -
>  kernel/events/core.c       | 4 ----
>  2 files changed, 5 deletions(-)
> 
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index 1a8942277dda..509ae4770bbe 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -931,7 +931,6 @@ struct perf_event_context {
>  	struct list_head		event_list;
>  
>  	int				nr_events;
> -	int				nr_user;
>  	int				is_active;
>  
>  	int				nr_task_data;
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index aa3450bdc227..6f44755ae907 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -1793,8 +1793,6 @@ list_add_event(struct perf_event *event, struct perf_event_context *ctx)
>  
>  	list_add_rcu(&event->event_entry, &ctx->event_list);
>  	ctx->nr_events++;
> -	if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
> -		ctx->nr_user++;
>  	if (event->attr.inherit_stat)
>  		ctx->nr_stat++;
>  
> @@ -2017,8 +2015,6 @@ list_del_event(struct perf_event *event, struct perf_event_context *ctx)
>  	event->attach_state &= ~PERF_ATTACH_CONTEXT;
>  
>  	ctx->nr_events--;
> -	if (event->hw.flags & PERF_EVENT_FLAG_USER_READ_CNT)
> -		ctx->nr_user--;
>  	if (event->attr.inherit_stat)
>  		ctx->nr_stat--;
>  
> -- 
> 2.43.5
>