From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Dario Binacchi <dariobin@libero.it>
Cc: Kurt Van Dijck <dev.kurt@vandijck-laurijssen.be>,
linux-kernel@vger.kernel.org,
Federico Vaga <federico.vaga@gmail.com>,
Alexander Stein <alexander.stein@systec-electronic.com>,
"David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Oliver Hartkopp <socketcan@hartkopp.net>,
Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Wolfgang Grandegger <wg@grandegger.com>,
YueHaibing <yuehaibing@huawei.com>,
Zhang Qilong <zhangqilong3@huawei.com>,
linux-can@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH v3 5/6] can: c_can: prepare to up the message objects number
Date: Wed, 3 Mar 2021 10:00:36 +0100 [thread overview]
Message-ID: <20210303090036.aocqk6gp3vqnzaku@pengutronix.de> (raw)
In-Reply-To: <91394876.26757.1614759793793@mail1.libero.it>
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On 03.03.2021 09:23:13, Dario Binacchi wrote:
[...]
> > > @@ -1205,17 +1203,31 @@ static int c_can_close(struct net_device *dev)
> > > return 0;
> > > }
> > >
> > > -struct net_device *alloc_c_can_dev(void)
> > > +struct net_device *alloc_c_can_dev(int msg_obj_num)
> > > {
> > > struct net_device *dev;
> > > struct c_can_priv *priv;
> > > + int msg_obj_tx_num = msg_obj_num / 2;
> >
> > IMO, a bigger tx queue is not usefull.
> > A bigger rx queue however is.
>
> This would not be good for my application. I think it really depends
> on the type of application. We can probably say that being able to
> size rx/tx queue would be a useful feature.
Ok. There is an ethtool interface to configure the size of the RX and TX
queues. In ethtool it's called the RX/TX "ring" size and you can get it
via the -g parameter, e.g. here for by Ethernet interface:
| $ ethtool -g enp0s25
| Ring parameters for enp0s25:
| Pre-set maximums:
| RX: 4096
| RX Mini: n/a
| RX Jumbo: n/a
| TX: 4096
| Current hardware settings:
| RX: 256
| RX Mini: n/a
| RX Jumbo: n/a
| TX: 256
If I understand correctly patch 6 has some assumptions that RX and TX
are max 32. To support up to 64 RX objects, you have to convert:
- u32 -> u64
- BIT() -> BIT_ULL()
- GENMASK() -> GENMASK_ULL()
The register access has to be converted, too. For performance reasons
you want to do as least as possible. Which is probably the most
complicated.
In the flexcan driver I have a similar problem. The driver keeps masks,
which mailboxes are RX and which TX and I added wrapper functions to
minimize IO access:
https://elixir.bootlin.com/linux/v5.11/source/drivers/net/can/flexcan.c#L904
This should to IMHO into patch 6.
Adding the ethtool support and making the rings configurable would be a
separate patch.
regards,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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next prev parent reply other threads:[~2021-03-03 14:41 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-28 10:38 [PATCH v3 0/6] can: c_can: add support to 64 message objects Dario Binacchi
2021-02-28 10:38 ` [PATCH v3 1/6] can: c_can: remove unused code Dario Binacchi
2021-02-28 10:38 ` [PATCH v3 2/6] can: c_can: fix indentation Dario Binacchi
2021-02-28 10:38 ` [PATCH v3 3/6] can: c_can: fix control interface used by c_can_do_tx Dario Binacchi
2021-03-02 18:44 ` Kurt Van Dijck
2021-03-03 7:22 ` Dario Binacchi
2021-02-28 10:38 ` [PATCH v3 4/6] can: c_can: use 32-bit write to set arbitration register Dario Binacchi
2021-02-28 10:38 ` [PATCH v3 5/6] can: c_can: prepare to up the message objects number Dario Binacchi
2021-03-01 11:38 ` Marc Kleine-Budde
2021-03-01 13:08 ` Marc Kleine-Budde
2021-03-01 16:54 ` Marc Kleine-Budde
2021-03-01 17:24 ` Dario Binacchi
2021-03-01 19:46 ` Marc Kleine-Budde
2021-03-01 17:21 ` Dario Binacchi
2021-03-01 19:45 ` Marc Kleine-Budde
2021-03-02 10:50 ` Dario Binacchi
2021-03-02 10:56 ` Marc Kleine-Budde
2021-03-02 18:49 ` Kurt Van Dijck
2021-03-03 8:23 ` Dario Binacchi
2021-03-03 9:00 ` Marc Kleine-Budde [this message]
2021-03-03 10:31 ` Dario Binacchi
2021-03-03 10:36 ` Marc Kleine-Budde
2021-02-28 10:38 ` [PATCH v3 6/6] can: c_can: add support to 64 message objects Dario Binacchi
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