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References: <20210309152354.95309-1-mailhol.vincent@wanadoo.fr> <20210309152354.95309-2-mailhol.vincent@wanadoo.fr>
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From:   Vincent MAILHOL <mailhol.vincent@wanadoo.fr>
Date:   Wed, 10 Mar 2021 03:00:43 +0900
Message-ID: <CAMZ6RqJ8e0sQPvaT_6dVOwisnHj6m+STgdnmLmmQxzV0+uHbvw@mail.gmail.com>
Subject: Re: [RFC PATCH 1/1] dql: add dql_set_min_limit()
To:     Marc Kleine-Budde <mkl@pengutronix.de>,
        linux-can <linux-can@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Tom Herbert <therbert@google.com>,
        Eric Dumazet <eric.dumazet@gmail.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Randy Dunlap <rdunlap@infradead.org>
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On Wed. 10 Mar 2021 at 00:23, Vincent Mailhol
<mailhol.vincent@wanadoo.fr> wrote:
>
> Add a function to set the dynamic queue limit minimum value.
>
> This function is to be used by network drivers which are able to
> prove, at least through empirical tests, that they reach better
> performances with a specific predefined dql.min_limit value.
>
> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
> ---
>  include/linux/dynamic_queue_limits.h | 3 +++
>  lib/dynamic_queue_limits.c           | 8 ++++++++
>  2 files changed, 11 insertions(+)
>
> diff --git a/include/linux/dynamic_queue_limits.h b/include/linux/dynamic_queue_limits.h
> index 407c2f281b64..32437f168a35 100644
> --- a/include/linux/dynamic_queue_limits.h
> +++ b/include/linux/dynamic_queue_limits.h
> @@ -103,6 +103,9 @@ void dql_reset(struct dql *dql);
>  /* Initialize dql state */
>  void dql_init(struct dql *dql, unsigned int hold_time);
>
> +/* Set the dql minimum limit */
> +void dql_set_min_limit(struct dql *dql, unsigned int min_limit);
> +
>  #endif /* _KERNEL_ */
>
>  #endif /* _LINUX_DQL_H */
> diff --git a/lib/dynamic_queue_limits.c b/lib/dynamic_queue_limits.c
> index fde0aa244148..8b6ad1e0a2e3 100644
> --- a/lib/dynamic_queue_limits.c
> +++ b/lib/dynamic_queue_limits.c
> @@ -136,3 +136,11 @@ void dql_init(struct dql *dql, unsigned int hold_time)
>         dql_reset(dql);
>  }
>  EXPORT_SYMBOL(dql_init);
> +
> +void dql_set_min_limit(struct dql *dql, unsigned int min_limit)
> +{
> +#ifdef CONFIG_BQL
> +       dql->min_limit = min_limit;
> +#endif

Marc pointed some issue on the #ifdef in a separate thread:
https://lore.kernel.org/linux-can/20210309153547.q7zspf46k6terxqv@pengutronix.de/

I will come back with a v2 tomorrow.

> +}
> +EXPORT_SYMBOL(dql_set_min_limit);