From: Tom Lendacky <thomas.lendacky@amd.com>
To: Jakub Kicinski <kubakici@wp.pl>
Cc: netdev@vger.kernel.org, David Miller <davem@davemloft.net>
Subject: Re: [PATCH net-next 08/12] amd-xgbe: Add ethtool show/set channels support
Date: Tue, 22 May 2018 08:24:09 -0500 [thread overview]
Message-ID: <6346850c-ea57-ef4e-db0a-78d29fd360b3@amd.com> (raw)
In-Reply-To: <20180521223542.3306664f@cakuba>
On 5/22/2018 12:35 AM, Jakub Kicinski wrote:
> On Mon, 21 May 2018 16:59:37 -0500, Tom Lendacky wrote:
>> + rx = combined + channels->rx_count;
>> + tx = combined + channels->tx_count;
>> + netdev_notice(netdev, "final channel count assignment: combined=%u, rx-only=%u, tx-only=%u\n",
>> + min(rx, tx), rx - min(rx, tx), tx - min(rx, tx));
>
> If user requests combined 0 rx 8 tx 8 they will end up with combined 8
> rx 0 tx 0. Is that expected?
Yes, which is the reason that I issue the final channel count message. I
debated on how to do all this and looked at other drivers as well as the
ethtool man page and decided on this logic.
>
> The man page clearly sayeth:
>
> -L --set-channels
> Changes the numbers of channels of the specified network device.
>
> rx N Changes the number of channels with only receive queues.
>
> tx N Changes the number of channels with only transmit queues.
>
> other N
> Changes the number of channels used only for other purposes
> e.g. link interrupts or SR-IOV co-ordination.
>
> combined N
> Changes the number of multi-purpose channels.
>
> Note the use of word *only*. There are drivers in tree which adhere to
> this interpretation and dutifully allocate separate IRQs if RX and TX
> channels are requested separately.
The amd-xgbe driver is not designed to allocate separate IRQs for Rx and
Tx. In general, there is one IRQ for a channel of which Tx and Rx are
shared. You can have more Tx channels than Rx channels or vice-versa, but
the min() of those numbers will be a combined Tx/Rx with the excess being
Tx or Rx only: e.g. combined 0 tx 8 rx 10 results in 8 combined channels
plus two Rx only channels.
I thought this was the most reasonable way to do this, please let me know
if there's a strong objection to this.
Thanks,
Tom
>
> Which is not to claim that majority of existing drivers adhere to this
> wording :)
>
next prev parent reply other threads:[~2018-05-22 13:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-21 21:58 [PATCH net-next 00/12] amd-xgbe: AMD XGBE driver updates 2018-05-21 Tom Lendacky
2018-05-21 21:58 ` [PATCH net-next 01/12] amd-xgbe: Fix debug output of max channel counts Tom Lendacky
2018-05-21 21:58 ` [PATCH net-next 02/12] amd-xgbe: Read and save the port property registers during probe Tom Lendacky
2018-05-21 21:58 ` [PATCH net-next 03/12] amd-xgbe: Remove use of comm_owned field Tom Lendacky
2018-05-21 21:58 ` [PATCH net-next 04/12] amd-xgbe: Remove field that indicates SFP diagnostic support Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 05/12] amd-xgbe: Add ethtool support to retrieve SFP module info Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 06/12] amd-xgbe: Add ethtool show/set ring parameter support Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 07/12] amd-xgbe: Prepare for ethtool set-channel support Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 08/12] amd-xgbe: Add ethtool show/set channels support Tom Lendacky
2018-05-22 5:35 ` Jakub Kicinski
2018-05-22 13:24 ` Tom Lendacky [this message]
2018-05-22 13:29 ` Edward Cree
2018-05-22 15:37 ` Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 09/12] amd-xgbe: Always attempt link training in KR mode Tom Lendacky
2018-05-21 21:59 ` [PATCH net-next 10/12] amd-xgbe: Advertise FEC support with the KR re-driver Tom Lendacky
2018-05-21 22:00 ` [PATCH net-next 11/12] amd-xgbe: Update the BelFuse quirk to support SGMII Tom Lendacky
2018-05-21 22:00 ` [PATCH net-next 12/12] amd-xgbe: Improve SFP 100Mbps auto-negotiation Tom Lendacky
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