From: Vinicius Costa Gomes <vinicius.gomes@intel•com>
To: Richard Cochran <richardcochran@gmail•com>
Cc: Miroslav Lichvar <mlichvar@redhat•com>,
Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel•com>,
netdev@vger•kernel.org, john.stultz@linaro•org,
Richard Cochran <rcochran@linutronix•de>,
jiri@resnulli•us, ivan.briano@intel•com, henrik@austad•us,
jhs@mojatatu•com, levi.pearson@harman•com,
intel-wired-lan@lists•osuosl.org, xiyou.wangcong@gmail•com,
tglx@linutronix•de, anna-maria@linutronix•de
Subject: Re: [Intel-wired-lan] [RFC v2 net-next 01/10] net: Add a new socket option for a future transmit time.
Date: Wed, 24 Jan 2018 14:46:24 -0800 [thread overview]
Message-ID: <87607qzxhb.fsf@intel.com> (raw)
In-Reply-To: <20180124030436.sukodrg2t3ckazu6@localhost>
Hi Richard,
Richard Cochran <richardcochran@gmail•com> writes:
> On Tue, Jan 23, 2018 at 01:22:37PM -0800, Vinicius Costa Gomes wrote:
>> What I think would be the ideal scenario would be if the clockid
>> parameter to the TBS Qdisc would not be necessary (if offload was
>> enabled), but that's not quite possible right now, because there's no
>> support for using the hrtimer infrastructure with dynamic clocks
>> (/dev/ptp*).
>
> We don't need hrtimer for HW offloading. Just enqueue the packets. I
> thought we agreed that user space get the ordering correct. In fact,
> davem insisted on it, IIRC.
About the ordering of packets, From here [1], there are 3 clear points
(in my understanding):
1. Re-ordering of TX descriptors on the device queue should/must not
happen;
2. Out of order requests are an error;
3. Timestamps in the past are an error;
The only robust way that we could think of about keeping the the packets
in order for the device queue is re-ordering packets in the Qdisc.
We tried to reach out for confirmation [2] of this understanding but
didn't receive any word.
Even if we reach a decision that the Qdisc should not re-order packets
(we wouldn't have any dependency on hrtimers in the offload case, as you
pointed out), we still need hrtimers for the software implementation.
So, I guess, the problem remains, if it's possible for the user to
express a /dev/ptp* clock, what should we do?
>
> Thanks,
> Richard
Cheers,
next prev parent reply other threads:[~2018-01-24 22:46 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-17 23:06 [RFC v2 net-next 00/10] Time based packet transmission Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 01/10] net: Add a new socket option for a future transmit time Jesus Sanchez-Palencia
2018-01-18 8:42 ` [Intel-wired-lan] " Miroslav Lichvar
2018-01-18 17:13 ` Richard Cochran
2018-02-01 0:49 ` Jesus Sanchez-Palencia
2018-02-01 4:16 ` Richard Cochran
2018-02-01 9:27 ` Miroslav Lichvar
2018-02-01 20:55 ` Jesus Sanchez-Palencia
2018-01-23 21:22 ` Vinicius Costa Gomes
2018-01-24 3:04 ` Richard Cochran
2018-01-24 22:46 ` Vinicius Costa Gomes [this message]
2018-01-26 2:12 ` Richard Cochran
2018-02-12 22:39 ` Jesus Sanchez-Palencia
2018-02-13 9:56 ` Miroslav Lichvar
2018-01-18 17:11 ` Richard Cochran
2018-01-23 18:12 ` Jesus Sanchez-Palencia
2018-01-19 21:15 ` Willem de Bruijn
2018-01-20 2:09 ` Richard Cochran
2018-01-25 9:12 ` [Intel-wired-lan] " Miroslav Lichvar
2018-01-25 16:52 ` Richard Cochran
2018-01-23 18:24 ` Jesus Sanchez-Palencia
2018-01-23 20:02 ` Willem de Bruijn
2018-01-17 23:06 ` [RFC v2 net-next 02/10] net: ipv4: raw: Hook into time based transmission Jesus Sanchez-Palencia
2018-01-18 0:28 ` Eric Dumazet
2018-01-17 23:06 ` [RFC v2 net-next 03/10] net: ipv4: udp: " Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 04/10] net: packet: " Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 05/10] net/sched: Allow creating a Qdisc watchdog with other clocks Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 06/10] net/sched: Introduce the TBS Qdisc Jesus Sanchez-Palencia
2018-01-18 13:35 ` Jamal Hadi Salim
2018-01-18 13:44 ` Jamal Hadi Salim
2018-01-23 21:45 ` Jesus Sanchez-Palencia
2018-01-18 17:18 ` Richard Cochran
2018-01-23 22:01 ` Jesus Sanchez-Palencia
2018-01-19 21:18 ` Willem de Bruijn
2018-01-17 23:06 ` [RFC v2 net-next 07/10] igb: Refactor igb_configure_cbs() Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 08/10] igb: Only change Tx arbitration when CBS is on Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 09/10] igb: Refactor igb_offload_cbs() Jesus Sanchez-Palencia
2018-01-17 23:06 ` [RFC v2 net-next 10/10] igb: Add support for TBS offload Jesus Sanchez-Palencia
2018-01-23 5:23 ` [RFC v2 net-next 00/10] Time based packet transmission Richard Cochran
2018-01-23 5:26 ` Richard Cochran
2018-01-23 18:07 ` Jesus Sanchez-Palencia
2018-01-24 1:43 ` Levi Pearson
2018-01-27 0:04 ` Jesus Sanchez-Palencia
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