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From: Slava Ovsiienko <viacheslavo@mellanox.com>
To: Didier Pallard <didier.pallard@6wind.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"stable@dpdk.org" <stable@dpdk.org>,
	Matan Azrad <matan@mellanox.com>
Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH] net/mlx5: fix Rx descriptor status returned value
Date: Tue, 17 Mar 2020 09:25:25 +0000
Message-ID: <AM4PR05MB32658369979987E40EF10237D2F60@AM4PR05MB3265.eurprd05.prod.outlook.com> (raw)
In-Reply-To: <CAMinK27-syP=xv-j+KdynqoNx26KKEu19L1txyF=nJ7L1CA=aA@mail.gmail.com>

From: Didier Pallard <didier.pallard@6wind.com>
Sent: Tuesday, March 17, 2020 11:19
To: Slava Ovsiienko <viacheslavo@mellanox.com>
Cc: dev@dpdk.org; stable@dpdk.org; Matan Azrad <matan@mellanox.com>
Subject: Re: [dpdk-dev] [PATCH] net/mlx5: fix Rx descriptor status returned value
>>>well, please do if you don't mind,
OK, I will.

>>>You will validate it quicker, and I'm currently working on a different topic.
>>>Btw, do you think it's possible to have an implementation of [r,t]x_status_descriptor functions for vectorized implementation?
>>>thanks
Yes, we are planning this update.

With best regards, Slava


didier

On Tue, Mar 17, 2020 at 9:33 AM Slava Ovsiienko <viacheslavo@mellanox.com<mailto:viacheslavo@mellanox.com>> wrote:
>> From: Didier Pallard <didier.pallard@6wind.com<mailto:didier.pallard@6wind.com>>
>> Sent: Monday, March 16, 2020 19:24
>> To: Slava Ovsiienko <viacheslavo@mellanox.com<mailto:viacheslavo@mellanox.com>>
>> Cc: dev@dpdk.org<mailto:dev@dpdk.org>; stable@dpdk.org<mailto:stable@dpdk.org>; Matan Azrad <matan@mellanox.com<mailto:matan@mellanox.com>>
>> Subject: Re: [dpdk-dev] [PATCH] net/mlx5: fix Rx descriptor status returned value
>> Well, you're right, another way to fix the problem could be to set up the queue size assuming the provided number
>> is a number of packets in queue rather than a number of mbufs in queue.

Yes, it is intended in queue setup routine. But, for mlx5 we have a bug for regular mlx5_rx_burst if scattering is enabled,
the Rx queue is created with size wqe_n elements, should be wqe_n << sges_n instead, to be able to receive the requested
number of packets (wqe_n). I think we must fix. Would you like to update your patch, or should I provide mine?

>> But not sure it's better, it's also important for the application/user to know the number of mbufs that could fit in a rx/tx queue,
>> whatever the number of packets that it covers, since it is very important to size the memory pools correctly to avoid any
>> mbuf shortage during system life.
>> Thanks
>> Didier
To estimate - the number of "DPDK descriptors" should be multiplied by the maximal length of scattered packet chain.

With best regards, Slava

> -----Original Message-----
> From: dev <mailto:dev-bounces@dpdk.org<mailto:dev-bounces@dpdk.org>> On Behalf Of Didier Pallard
> Sent: Friday, March 13, 2020 11:57
> To: mailto:dev@dpdk.org<mailto:dev@dpdk.org>
> Cc: mailto:stable@dpdk.org<mailto:stable@dpdk.org>
> Subject: [dpdk-dev] [PATCH] net/mlx5: fix Rx descriptor status returned value
>
> Two bugs in rx_queue_count function:
> - One entry may contain several segments, so 'used' must be multiplied
>   by number of segments per entry to properly reflect the queue usage.
> - rx_queue_count returns the number of entries used in queue, so it ranges
>   from 0 to max number of entries in queue, not this number minus
>   one.
>
> Fixes: 8788fec1f269 ("net/mlx5: implement descriptor status API")
> Cc: mailto:stable@dpdk.org<mailto:stable@dpdk.org>
> Signed-off-by: Didier Pallard <mailto:didier.pallard@6wind.com<mailto:didier.pallard@6wind.com>>
> ---
>  drivers/net/mlx5/mlx5_rxtx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/mlx5/mlx5_rxtx.c b/drivers/net/mlx5/mlx5_rxtx.c index
> 5ac63da8039d..17f80c25443e 100644
> --- a/drivers/net/mlx5/mlx5_rxtx.c
> +++ b/drivers/net/mlx5/mlx5_rxtx.c
> @@ -500,7 +500,7 @@ rx_queue_count(struct mlx5_rxq_data *rxq)
>               used += n;
>               cqe = &(*rxq->cqes)[cq_ci & cqe_cnt];
>       }
> -     used = RTE_MIN(used, (1U << rxq->elts_n) - 1);
> +     used = RTE_MIN(used * (1 << rxq->sges_n), 1U << rxq->elts_n);
>       return used;
>  }
>
> --
> 2.24.1

  reply	other threads:[~2020-03-17  9:25 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-13  9:56 [dpdk-stable] " Didier Pallard
2020-03-16 16:05 ` [dpdk-stable] [dpdk-dev] " Slava Ovsiienko
2020-03-16 17:24   ` Didier Pallard
2020-03-17  8:33     ` Slava Ovsiienko
2020-03-17  9:19       ` Didier Pallard
2020-03-17  9:25         ` Slava Ovsiienko [this message]
2020-03-17  9:41           ` Didier Pallard
2020-10-29 11:29           ` Didier Pallard

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