linux-kernel - Re: [PATCH v2 1/2] percpu: Add percpu_counter_add

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Message-ID: <20220905193159.eeu2xmqj6743kzxv@google.com>
Date:   Mon, 5 Sep 2022 19:31:59 +0000
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Jiebin Sun <jiebin.sun@...el.com>
Cc:     akpm@...ux-foundation.org, vasily.averin@...ux.dev,
        dennis@...nel.org, tj@...nel.org, cl@...ux.com,
        ebiederm@...ssion.com, legion@...nel.org, manfred@...orfullife.com,
        alexander.mikhalitsyn@...tuozzo.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, tim.c.chen@...el.com,
        feng.tang@...el.com, ying.huang@...el.com, tianyou.li@...el.com,
        wangyang.guo@...el.com
Subject: Re: [PATCH v2 1/2] percpu: Add percpu_counter_add_local

On Tue, Sep 06, 2022 at 03:35:16AM +0800, Jiebin Sun wrote:
> Add percpu_counter_add_local for only updating local counter
> without aggregating to global counter.

Please add why do we need this. Who should use this and who shouldn't.

> 
> Signed-off-by: Jiebin Sun <jiebin.sun@...el.com>

[...]

> diff --git a/lib/percpu_counter.c b/lib/percpu_counter.c
> index ed610b75dc32..d33cb750962a 100644
> --- a/lib/percpu_counter.c
> +++ b/lib/percpu_counter.c
> @@ -72,6 +72,12 @@ void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
>  }
>  EXPORT_SYMBOL(percpu_counter_set);
>

Add a doc comment here on why someone want to use this?

> +void percpu_counter_add_local(struct percpu_counter *fbc, s64 amount)
> +{
> +	this_cpu_add(*fbc->counters, amount);
> +}
> +EXPORT_SYMBOL(percpu_counter_add_local);
> +
>  /*
>   * This function is both preempt and irq safe. The former is due to explicit
>   * preemption disable. The latter is guaranteed by the fact that the slow path
> -- 
> 2.31.1
>