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From: Thomas Monjalon <thomas@monjalon.net>
To: 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>,
	"andrew.rybchenko@oktetlabs.ru" <andrew.rybchenko@oktetlabs.ru>
Subject: Re: [RFC v2 3/7] ethdev: introduce Rx queue based limit watermark
Date: Tue, 24 May 2022 10:18:02 +0200	[thread overview]
Message-ID: <31797171.aRNtrjHk3s@thomas> (raw)
In-Reply-To: <MN2PR12MB3647A056A4721B7283DC245FA8D79@MN2PR12MB3647.namprd12.prod.outlook.com>

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?



  reply	other threads:[~2022-05-24  8:18 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 [this message]
2022-05-25 12:59                   ` Andrew Rybchenko
2022-05-25 13:58                     ` Thomas Monjalon
2022-05-25 14:23                       ` Andrew Rybchenko
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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