From: Olivier Matz <olivier.matz@6wind.com>
To: Andrew Rybchenko <arybchenko@solarflare.com>
Cc: <dev@dpdk.org>, <thomas.monjalon@6wind.com>,
<konstantin.ananyev@intel.com>, <wenzhuo.lu@intel.com>,
<helin.zhang@intel.com>, <jingjing.wu@intel.com>,
<adrien.mazarguil@6wind.com>, <nelio.laranjeiro@6wind.com>,
<ferruh.yigit@intel.com>, <bruce.richardson@intel.com>
Subject: Re: [dpdk-dev] [PATCH 1/6] ethdev: add descriptor status API
Date: Thu, 2 Mar 2017 15:54:32 +0100 [thread overview]
Message-ID: <20170302155432.7e81e969@platinum> (raw)
In-Reply-To: <d57af8bc-a4b5-427f-aa9f-dbc8a6bb60c7@solarflare.com>
> >>> + * Check the status of a Rx descriptor in the queue
> >> I think it would be useful to highlight caller context.
> >> Should it be the same CPU which receives packets from the queue?
> > Yes, you are right it would be useful. I suggest the following sentences:
> >
> > This function should be called on a dataplane core like the
> > Rx function. They should not be called concurrently on the same
> > queue.
>
> The first sentence looks fine. "They" (functions?, dataplane cores?) is
> unclear for me in the second. May be the first one is simply sufficient.
Ok, I'll keep the first one at least, and see if I can reword the
second one to make it clear.
> >>> + *
> >>> + * @param port_id
> >>> + * The port identifier of the Ethernet device.
> >>> + * @param queue_id
> >>> + * The Rx queue identifier on this port.
> >>> + * @param offset
> >>> + * The offset of the descriptor starting from tail (0 is the next
> >>> + * packet to be received by the driver).
> >>> + * @return
> >>> + * - (RTE_ETH_DESC_AVAIL): Descriptor is available for the hardware to
> >>> + * receive a packet.
> >>> + * - (RTE_ETH_DESC_DONE): Descriptor is done, it is filled by hw, but
> >>> + * not yet processed by the driver (i.e. in the receive queue).
> >>> + * - (RTE_ETH_DESC_USED): Descriptor is unavailable (hold by driver,
> >>> + * not yet returned to hw).
> >> It looks like it is the most suitable for descriptors which are reserved
> >> and never used.
> > Can you give some more details about what is a reserved but never
> > used descriptor? (same question for Tx)
>
> Our HW has a requirement to keep few descriptors always unused (i.e.
> some gap between tail and head). It is just a few descriptors, but
> invalid descriptor status may misguide application. E.g. if Rx queue
> size is 512 and offset 510, it will always be unused (since it is
> reserved). It is not an indication that core is too slow and can't keep
> the pace.
Understood.
I can change _USED into _UNAVAIL (add it for Tx), with the following
description:
- (RTE_ETH_DESC_UNAVAIL): Descriptor is unavailable: either hold by driver
and not yet returned to hw, or reserved by the hardware.
next prev parent reply other threads:[~2017-03-02 14:54 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-24 9:54 [dpdk-dev] [RFC 0/9] get Rx and Tx used descriptors Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 1/9] ethdev: clarify api comments of rx queue count Olivier Matz
2016-11-24 10:52 ` Ferruh Yigit
2016-11-24 11:13 ` Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 2/9] ethdev: move queue id check in generic layer Olivier Matz
2016-11-24 10:59 ` Ferruh Yigit
2016-11-24 13:05 ` Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 3/9] ethdev: add handler for Tx queue descriptor count Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 4/9] net/ixgbe: optimize Rx " Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 5/9] net/ixgbe: add handler for Tx " Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 6/9] net/igb: optimize rx " Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 7/9] net/igb: add handler for tx " Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 8/9] net/e1000: optimize rx " Olivier Matz
2016-11-24 9:54 ` [dpdk-dev] [RFC 9/9] net/e1000: add handler for tx " Olivier Matz
2017-01-13 16:44 ` [dpdk-dev] [RFC 0/9] get Rx and Tx used descriptors Olivier Matz
2017-01-13 17:32 ` Richardson, Bruce
2017-01-17 8:24 ` Olivier Matz
2017-01-17 13:56 ` Bruce Richardson
2017-03-01 17:19 ` [dpdk-dev] [PATCH 0/6] get status of Rx and Tx descriptors Olivier Matz
2017-03-01 17:19 ` [dpdk-dev] [PATCH 1/6] ethdev: add descriptor status API Olivier Matz
2017-03-01 18:22 ` Andrew Rybchenko
2017-03-02 13:57 ` Olivier Matz
2017-03-02 14:19 ` Andrew Rybchenko
2017-03-02 14:54 ` Olivier Matz [this message]
2017-03-02 15:05 ` Andrew Rybchenko
2017-03-02 15:14 ` Olivier Matz
2017-03-01 17:19 ` [dpdk-dev] [PATCH 2/6] net/ixgbe: implement " Olivier Matz
2017-03-01 17:19 ` [dpdk-dev] [PATCH 3/6] net/e1000: implement descriptor status API (igb) Olivier Matz
2017-03-02 1:28 ` Lu, Wenzhuo
2017-03-02 13:58 ` Olivier Matz
2017-03-01 17:19 ` [dpdk-dev] [PATCH 4/6] net/e1000: implement descriptor status API (em) Olivier Matz
2017-03-02 1:22 ` Lu, Wenzhuo
2017-03-02 14:46 ` Olivier Matz
2017-03-03 1:15 ` Lu, Wenzhuo
2017-03-01 17:19 ` [dpdk-dev] [PATCH 5/6] net/mlx5: implement descriptor status API Olivier Matz
2017-03-02 7:56 ` Nélio Laranjeiro
2017-03-01 17:19 ` [dpdk-dev] [PATCH 6/6] net/i40e: " Olivier Matz
2017-03-01 18:02 ` [dpdk-dev] [PATCH 0/6] get status of Rx and Tx descriptors Andrew Rybchenko
2017-03-02 13:40 ` Olivier Matz
2017-03-06 10:41 ` Thomas Monjalon
2017-03-01 18:07 ` Stephen Hemminger
2017-03-02 13:43 ` Olivier Matz
2017-03-06 10:41 ` Thomas Monjalon
2017-03-02 15:32 ` Bruce Richardson
2017-03-02 16:14 ` Olivier Matz
2017-03-03 16:18 ` Venkatesan, Venky
2017-03-03 16:45 ` Olivier Matz
2017-03-03 18:46 ` Venkatesan, Venky
2017-03-04 20:45 ` Olivier Matz
2017-03-06 11:02 ` Thomas Monjalon
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 " Olivier Matz
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 1/6] ethdev: add descriptor status API Olivier Matz
2017-03-09 11:49 ` Andrew Rybchenko
2017-03-21 8:32 ` Yang, Qiming
2017-03-24 12:49 ` Olivier Matz
2017-03-27 1:28 ` Yang, Qiming
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 2/6] net/ixgbe: implement " Olivier Matz
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 3/6] net/e1000: implement descriptor status API (igb) Olivier Matz
2017-03-08 1:17 ` Lu, Wenzhuo
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 4/6] net/e1000: implement descriptor status API (em) Olivier Matz
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 5/6] net/mlx5: implement descriptor status API Olivier Matz
2017-03-07 15:59 ` [dpdk-dev] [PATCH v2 6/6] net/i40e: " Olivier Matz
2017-03-08 1:17 ` Lu, Wenzhuo
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 0/6] get status of Rx and Tx descriptors Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 1/6] ethdev: add descriptor status API Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 2/6] net/ixgbe: implement " Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 3/6] net/e1000: implement descriptor status API (igb) Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 4/6] net/e1000: implement descriptor status API (em) Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 5/6] net/mlx5: implement descriptor status API Olivier Matz
2017-03-29 8:36 ` [dpdk-dev] [PATCH v3 6/6] net/i40e: " Olivier Matz
2017-03-30 13:30 ` [dpdk-dev] [PATCH v3 0/6] get status of Rx and Tx descriptors Thomas Monjalon
2017-04-19 15:50 ` Ferruh Yigit
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