From: Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>
To: Thomas Monjalon <thomas@monjalon.net>,
Stephen Hemminger <stephen@networkplumber.org>,
Spike Du <spiked@nvidia.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, Matan Azrad <matan@nvidia.com>,
Slava Ovsiienko <viacheslavo@nvidia.com>,
Ori Kam <orika@nvidia.com>, Raslan Darawsheh <rasland@nvidia.com>,
"ferruh.yigit@amd.com" <ferruh.yigit@amd.com>
Subject: Re: [RFC v2 3/7] ethdev: introduce Rx queue based limit watermark
Date: Wed, 25 May 2022 17:23:41 +0300 [thread overview]
Message-ID: <9134a987-5b7e-74df-7366-70bbdd4792e1@oktetlabs.ru> (raw)
In-Reply-To: <1740079.OQMrUlzKSU@thomas>
On 5/25/22 16:58, Thomas Monjalon wrote:
> 25/05/2022 14:59, Andrew Rybchenko:
>> On 5/24/22 11:18, Thomas Monjalon wrote:
>>> 24/05/2022 04:50, Spike Du:
>>>> From: Thomas Monjalon <thomas@monjalon.net>
>>>>> 23/05/2022 05:01, Spike Du:
>>>>>> From: Stephen Hemminger <stephen@networkplumber.org>
>>>>>>> Spike Du <spiked@nvidia.com> wrote:
>>>>>>>> --- a/lib/ethdev/rte_ethdev.h
>>>>>>>> +++ b/lib/ethdev/rte_ethdev.h
>>>>>>>> @@ -1249,7 +1249,16 @@ struct rte_eth_rxconf {
>>>>>>>> */
>>>>>>>> union rte_eth_rxseg *rx_seg;
>>>>>>>>
>>>>>>>> - uint64_t reserved_64s[2]; /**< Reserved for future fields */
>>>>>>>> + /**
>>>>>>>> + * Per-queue Rx limit watermark defined as percentage of Rx queue
>>>>>>>> + * size. If Rx queue receives traffic higher than this percentage,
>>>>>>>> + * the event RTE_ETH_EVENT_RX_LWM is triggered.
>>>>>>>> + */
>>>>>>>> + uint8_t lwm;
>>>>>>>> +
>>>>>>>> + uint8_t reserved_bits[3];
>>>>>>>> + uint32_t reserved_32s;
>>>>>>>> + uint64_t reserved_64s;
>>>>>>>
>>>>>>> Ok but, this is an ABI risk about this because reserved stuff was
>>>>>>> never required before.
>>>>>
>>>>> An ABI compatibility issue would be for an application compiled with an old
>>>>> DPDK, and loading a new DPDK at runtime.
>>>>> Let's think what would happen in such a case.
>>>>>
>>>>>>> Whenever is a reserved field is introduced the code (in this case
>>>>>>> rte_ethdev_configure).
>>>>>
>>>>> rte_eth_rx_queue_setup() is called with rx_conf->lwm not initialized.
>>>>> Then the library and drivers may interpret a wrong value.
>>>>>
>>>>>>> Best practice would have been to have the code require all reserved
>>>>>>> fields be
>>>>>>> 0 in earlier releases. In this case an application is like to define
>>>>>>> a watermark of zero; how will your code handle it.
>>>>>>
>>>>>> Having watermark of 0 is desired, which is the default. LWM of 0 means
>>>>>> the Rx Queue's watermark is not monitored, hence no LWM event is
>>>>> generated.
>>>>>
>>>>> The problem is to have a value not initialized.
>>>>> I think the best approach is to not expose the LWM value through this
>>>>> configuration structure.
>>>>> If the need is to get the current value, we should better add a field in the
>>>>> struct rte_eth_rxq_info.
>>>>
>>>> At least from all the dpdk app/example code, rxconf is initialized to 0 then setup
>>>> The Rx queue, if user follows these examples we should not have ABI issue.
>>>> Since many people are concerned about rxconf change, it's ok to remove the LWM
>>>> Field there.
>>>> Yes, I think we can add lwm into rte_eth_rxq_info. If we can set Rx queue's attribute,
>>>> We should have a way to get it.
>>>
>>> Unfortunately we cannot rely on examples for ABI compatibility.
>>> My suggestion of moving the field in rte_eth_rxq_info
>>> is not obvious because it could change the size of the struct.
>>> But thanks to __rte_cache_min_aligned, it is OK.
>>> Running pahole on this struct shows we have 50 bytes free:
>>> /* size: 128, cachelines: 2, members: 6 */
>>> /* padding: 50 */
>>>
>>> The other option would be to get the LWM value with a "get" function.
>>>
>>> What others prefer?
>>
>> If I'm not mistaken the changeset breaks ABI in any case since
>> it adds a new event and changes MAX.
>
> I think we can consider it as not a breakage (a rule should be added).
> Last time we had to update this enum, this was the conclusion:
> from https://git.dpdk.org/dpdk/commit/?id=44bf3c796be3f
> "
> The new event type addition in the enum is flagged as an ABI breakage,
> so an ignore rule is added for these reasons:
> - It is not changing value of existing types (except MAX)
> - The new value is not used by existing API if the event is not
> registered
> In general, it is safe adding new ethdev event types at the end of the
> enum, because of event callback registration mechanism.
> "
I see. Makes sense. Thanks for the information.
>> If so, I'd wait for the
>> next ABI breaking release and do not touch reserved fields.
>
> In any case, rte_eth_rxconf is not a good fit
> because we have a separate function for configuration.
Yes, it is better to avoid two ways to configure the same
thing.
> It should be either in rte_eth_rxq_info or a specific "get" function.
I see no point to introduce specific get function for a single
value. I think that rte_eth_rxq_info is the right way to get
current value.
next prev parent reply other threads:[~2022-05-25 14:23 UTC|newest]
Thread overview: 131+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-01 3:22 [RFC 0/6] net/mlx5: introduce limit watermark and host shaper Spike Du
2022-04-01 3:22 ` [RFC 1/6] net/mlx5: add LWM support for Rxq Spike Du
2022-05-06 3:56 ` [RFC v1 0/7] net/mlx5: introduce limit watermark and host shaper Spike Du
2022-05-06 3:56 ` [RFC v1 1/7] net/mlx5: add LWM support for Rxq Spike Du
2022-05-06 3:56 ` [RFC v1 2/7] common/mlx5: share interrupt management Spike Du
2022-05-06 3:56 ` [RFC v1 3/7] ethdev: introduce Rx queue based limit watermark Spike Du
2022-05-19 9:37 ` Andrew Rybchenko
2022-05-06 3:56 ` [RFC v1 4/7] net/mlx5: add LWM event handling support Spike Du
2022-05-06 3:56 ` [RFC v1 5/7] net/mlx5: support Rx queue based limit watermark Spike Du
2022-05-06 3:56 ` [RFC v1 6/7] net/mlx5: add private API to config host port shaper Spike Du
2022-05-06 3:56 ` [RFC v1 7/7] app/testpmd: add LWM and Host Shaper command Spike Du
2022-05-22 5:58 ` [RFC v2 0/7] introduce per-queue limit watermark and host shaper Spike Du
2022-05-22 5:58 ` [RFC v2 1/7] net/mlx5: add LWM support for Rxq Spike Du
2022-05-22 5:58 ` [RFC v2 2/7] common/mlx5: share interrupt management Spike Du
2022-05-22 5:58 ` [RFC v2 3/7] ethdev: introduce Rx queue based limit watermark Spike Du
2022-05-22 15:23 ` Stephen Hemminger
2022-05-23 3:01 ` Spike Du
2022-05-23 21:45 ` Thomas Monjalon
2022-05-24 2:50 ` Spike Du
2022-05-24 8:18 ` Thomas Monjalon
2022-05-25 12:59 ` Andrew Rybchenko
2022-05-25 13:58 ` Thomas Monjalon
2022-05-25 14:23 ` Andrew Rybchenko [this message]
2022-05-23 22:54 ` Stephen Hemminger
2022-05-24 3:46 ` Spike Du
2022-05-22 15:24 ` Stephen Hemminger
2022-05-23 2:18 ` Spike Du
2022-05-23 6:07 ` Morten Brørup
2022-05-23 10:58 ` Thomas Monjalon
2022-05-23 14:10 ` Spike Du
2022-05-23 14:39 ` Thomas Monjalon
2022-05-24 6:35 ` Andrew Rybchenko
2022-05-24 9:40 ` Morten Brørup
2022-05-22 5:58 ` [RFC v2 4/7] net/mlx5: add LWM event handling support Spike Du
2022-05-22 5:58 ` [RFC v2 5/7] net/mlx5: support Rx queue based limit watermark Spike Du
2022-05-22 5:58 ` [RFC v2 6/7] net/mlx5: add private API to config host port shaper Spike Du
2022-05-22 5:59 ` [RFC v2 7/7] app/testpmd: add LWM and Host Shaper command Spike Du
2022-05-24 15:20 ` [PATCH v3 0/7] introduce per-queue limit watermark and host shaper Spike Du
2022-05-24 15:20 ` [PATCH v3 1/7] net/mlx5: add LWM support for Rxq Spike Du
2022-05-24 15:20 ` [PATCH v3 2/7] common/mlx5: share interrupt management Spike Du
2022-05-24 15:20 ` [PATCH v3 3/7] ethdev: introduce Rx queue based limit watermark Spike Du
2022-05-24 15:20 ` [PATCH v3 4/7] net/mlx5: add LWM event handling support Spike Du
2022-05-24 15:20 ` [PATCH v3 5/7] net/mlx5: support Rx queue based limit watermark Spike Du
2022-05-24 15:20 ` [PATCH v3 6/7] net/mlx5: add private API to config host port shaper Spike Du
2022-05-24 15:20 ` [PATCH v3 7/7] app/testpmd: add LWM and Host Shaper command Spike Du
2022-05-24 15:59 ` [PATCH v3 0/7] introduce per-queue limit watermark and host shaper Thomas Monjalon
2022-05-24 19:00 ` Morten Brørup
2022-05-24 19:22 ` Thomas Monjalon
2022-05-25 14:11 ` Andrew Rybchenko
2022-05-25 13:14 ` Spike Du
2022-05-25 13:40 ` Morten Brørup
2022-05-25 13:59 ` Spike Du
2022-05-25 14:16 ` Morten Brørup
2022-05-25 14:30 ` Andrew Rybchenko
2022-06-03 12:48 ` [PATCH v4 0/7] introduce per-queue fill threshold " Spike Du
2022-06-03 12:48 ` [PATCH v4 1/7] net/mlx5: add LWM support for Rxq Spike Du
2022-06-03 12:48 ` [PATCH v4 2/7] common/mlx5: share interrupt management Spike Du
2022-06-03 14:30 ` Ray Kinsella
2022-06-03 12:48 ` [PATCH v4 3/7] ethdev: introduce Rx queue based fill threshold Spike Du
2022-06-03 14:30 ` Ray Kinsella
2022-06-04 12:46 ` Andrew Rybchenko
2022-06-06 13:16 ` Spike Du
2022-06-06 17:15 ` Andrew Rybchenko
2022-06-06 21:30 ` Thomas Monjalon
2022-06-07 8:02 ` Andrew Rybchenko
2022-06-07 6:00 ` Spike Du
2022-06-06 15:49 ` Stephen Hemminger
2022-06-03 12:48 ` [PATCH v4 4/7] net/mlx5: add LWM event handling support Spike Du
2022-06-03 12:48 ` [PATCH v4 5/7] net/mlx5: support Rx queue based fill threshold Spike Du
2022-06-03 12:48 ` [PATCH v4 6/7] net/mlx5: add private API to config host port shaper Spike Du
2022-06-03 14:55 ` Ray Kinsella
2022-06-03 12:48 ` [PATCH v4 7/7] app/testpmd: add Host Shaper command Spike Du
2022-06-07 12:59 ` [PATCH v5 0/7] introduce per-queue available descriptor threshold and host shaper Spike Du
2022-06-07 12:59 ` [PATCH v5 1/7] net/mlx5: add LWM support for Rxq Spike Du
2022-06-08 20:10 ` Matan Azrad
2022-06-07 12:59 ` [PATCH v5 2/7] common/mlx5: share interrupt management Spike Du
2022-06-07 12:59 ` [PATCH v5 3/7] ethdev: introduce Rx queue based available descriptor threshold Spike Du
2022-06-07 12:59 ` [PATCH v5 4/7] net/mlx5: add LWM event handling support Spike Du
2022-06-07 12:59 ` [PATCH v5 5/7] net/mlx5: support Rx queue based available descriptor threshold Spike Du
2022-06-07 12:59 ` [PATCH v5 6/7] net/mlx5: add private API to config host port shaper Spike Du
2022-06-07 12:59 ` [PATCH v5 7/7] app/testpmd: add Host Shaper command Spike Du
2022-06-09 7:55 ` Andrew Rybchenko
2022-06-10 2:22 ` Spike Du
2022-06-13 2:50 ` [PATCH v6] " Spike Du
2022-06-13 2:50 ` Spike Du
2022-06-14 9:43 ` Singh, Aman Deep
2022-06-14 9:54 ` Spike Du
2022-06-14 12:01 ` [PATCH v7] " Spike Du
2022-06-14 12:01 ` Spike Du
2022-06-15 7:51 ` Matan Azrad
2022-06-15 11:08 ` Thomas Monjalon
2022-06-15 12:58 ` [PATCH v8 0/6] introduce per-queue available descriptor threshold and host shaper Spike Du
2022-06-15 12:58 ` [PATCH v8 1/6] net/mlx5: add LWM support for Rxq Spike Du
2022-06-15 14:43 ` [PATCH v9 0/6] introduce per-queue available descriptor threshold and host shaper Spike Du
2022-06-15 14:43 ` [PATCH v9 1/6] net/mlx5: add LWM support for Rxq Spike Du
2022-06-16 8:41 ` [PATCH v10 0/6] introduce per-queue available descriptor threshold and host shaper Spike Du
2022-06-16 8:41 ` [PATCH v10 1/6] net/mlx5: add LWM support for Rxq Spike Du
2022-06-16 8:41 ` [PATCH v10 2/6] common/mlx5: share interrupt management Spike Du
2022-06-23 16:05 ` Ray Kinsella
2022-06-16 8:41 ` [PATCH v10 3/6] net/mlx5: add LWM event handling support Spike Du
2022-06-16 8:41 ` [PATCH v10 4/6] net/mlx5: support Rx queue based available descriptor threshold Spike Du
2022-06-16 8:41 ` [PATCH v10 5/6] net/mlx5: add private API to config host port shaper Spike Du
2022-06-16 8:41 ` [PATCH v10 6/6] app/testpmd: add Host Shaper command Spike Du
2022-06-19 8:14 ` [PATCH v10 0/6] introduce per-queue available descriptor threshold and host shaper Raslan Darawsheh
2022-06-15 14:43 ` [PATCH v9 2/6] common/mlx5: share interrupt management Spike Du
2022-06-15 14:43 ` [PATCH v9 3/6] net/mlx5: add LWM event handling support Spike Du
2022-06-15 14:43 ` [PATCH v9 4/6] net/mlx5: support Rx queue based available descriptor threshold Spike Du
2022-06-15 14:43 ` [PATCH v9 5/6] net/mlx5: add private API to config host port shaper Spike Du
2022-06-15 14:43 ` [PATCH v9 6/6] app/testpmd: add Host Shaper command Spike Du
2022-06-15 12:58 ` [PATCH v8 2/6] common/mlx5: share interrupt management Spike Du
2022-06-15 12:58 ` [PATCH v8 3/6] net/mlx5: add LWM event handling support Spike Du
2022-06-15 12:58 ` [PATCH v8 4/6] net/mlx5: support Rx queue based available descriptor threshold Spike Du
2022-06-15 12:58 ` [PATCH v8 5/6] net/mlx5: add private API to config host port shaper Spike Du
2022-06-15 12:58 ` [PATCH v8 6/6] app/testpmd: add Host Shaper command Spike Du
2022-06-08 9:43 ` [PATCH v5 0/7] introduce per-queue available descriptor threshold and host shaper Andrew Rybchenko
2022-06-08 16:35 ` [PATCH v6] ethdev: introduce available Rx descriptors threshold Andrew Rybchenko
2022-06-08 17:22 ` Thomas Monjalon
2022-06-08 17:46 ` Thomas Monjalon
2022-06-09 0:17 ` fengchengwen
2022-06-09 7:05 ` Thomas Monjalon
2022-06-10 0:01 ` fengchengwen
2022-04-01 3:22 ` [RFC 2/6] common/mlx5: share interrupt management Spike Du
2022-04-01 3:22 ` [RFC 3/6] net/mlx5: add LWM event handling support Spike Du
2022-04-01 3:22 ` [RFC 4/6] net/mlx5: add private API to configure Rxq LWM Spike Du
2022-04-01 3:22 ` [RFC 5/6] net/mlx5: add private API to config host port shaper Spike Du
2022-04-01 3:22 ` [RFC 6/6] app/testpmd: add LWM and Host Shaper command Spike Du
2022-04-05 8:58 ` [RFC 0/6] net/mlx5: introduce limit watermark and host shaper Jerin Jacob
2022-04-26 2:42 ` Spike Du
2022-05-01 12:50 ` Jerin Jacob
2022-05-02 3:58 ` Spike Du
2022-04-29 5:48 ` Spike Du
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