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From: Olivier Matz <olivier.matz@6wind.com>
To: Bruce Richardson <bruce.richardson@intel.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
Subject: Re: [dpdk-dev] [PATCH 0/6] get status of Rx and Tx descriptors
Date: Thu, 2 Mar 2017 17:14:56 +0100	[thread overview]
Message-ID: <20170302171456.52a9415b@platinum> (raw)
In-Reply-To: <20170302153215.GA173492@bricha3-MOBL3.ger.corp.intel.com>

On Thu, 2 Mar 2017 15:32:15 +0000, Bruce Richardson <bruce.richardson@intel.com> wrote:
> On Wed, Mar 01, 2017 at 06:19:06PM +0100, Olivier Matz wrote:
> > This patchset introduces a new ethdev API:
> > - rte_eth_rx_descriptor_status()
> > - rte_eth_tx_descriptor_status()
> > 
> > The Rx API is aims to replace rte_eth_rx_descriptor_done() which
> > does almost the same, but does not differentiate the case of a
> > descriptor used by the driver (not returned to the hw).
> > 
> > The usage of these functions can be:
> > - on Rx, anticipate that the cpu is not fast enough to process
> >   all incoming packets, and take dispositions to solve the
> >   problem (add more cpus, drop specific packets, ...)
> > - on Tx, detect that the link is overloaded, and take dispositions
> >   to solve the problem (notify flow control, drop specific
> >   packets)
> >   
> Looking at it from a slightly higher level, are these APIs really going
> to help in these situations? If something is overloaded, doing more work
> by querying the ring status only makes things worse. I suspect that in
> most cases better results can be got by just looking at the results of
> RX and TX burst functions. For example, if RX burst is always returning
> a full set of packets, chances are you are overloaded, or at least have
> no scope for an unexpected burst or event.
> 
> Are these really needed for real applications? I suspect our trivial
> l3fwd power example can be made to work ok without them.

The l3fwd example uses the rte_eth_rx_descriptor_done() API, which
is very similar to what I'm adding here. The differences are:

- the new lib provides a Tx counterpart
- it differentiates done/avail/hold descriptors

The alternative was to update the descriptor_done API, but
I think we agreed to do that in this thread:
http://www.dpdk.org/ml/archives/dev/2017-January/054947.html

About the usefulness of the API, I confirm it is useful: for
instance, you can detect that you ring is more than half-full, and
take dispositions to increase your processing power or select the
packets you want to drop first.

Regards
Olivier

  reply	other threads:[~2017-03-02 16:14 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
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 [this message]
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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