From: "Zhao1, Wei" <wei.zhao1@intel.com>
To: "Morten Brørup" <mb@smartsharesystems.com>,
"Guo, Jia" <jia.guo@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
Thomas Monjalon <thomas@monjalon.net>,
"Yigit, Ferruh" <ferruh.yigit@intel.com>,
Andrew Rybchenko <arybchenko@solarflare.com>
Subject: Re: [dpdk-dev] ixgbe vector rx does not conform to rte_eth_rx_burst() API
Date: Thu, 16 Jul 2020 08:49:50 +0000 [thread overview]
Message-ID: <MWHPR11MB1391060094945333DE8AC929B77F0@MWHPR11MB1391.namprd11.prod.outlook.com> (raw)
In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35C61127@smartserver.smartshare.dk>
Hi,
> -----Original Message-----
> From: Morten Brørup <mb@smartsharesystems.com>
> Sent: Thursday, July 16, 2020 12:03 AM
> To: Zhao1, Wei <wei.zhao1@intel.com>; Guo, Jia <jia.guo@intel.com>
> Cc: dev@dpdk.org; Thomas Monjalon <thomas@monjalon.net>; Yigit, Ferruh
> <ferruh.yigit@intel.com>; Andrew Rybchenko <arybchenko@solarflare.com>
> Subject: ixgbe vector rx does not conform to rte_eth_rx_burst() API
>
> Wei, Jeff,
>
> For the ixgbe driver using vector functions, i.e. ixgbe_recv_pkts_vec(), calling
> rte_eth_rx_burst() with nb_pkts > RTE_IXGBE_MAX_RX_BURST only returns
> RTE_IXGBE_MAX_RX_BURST packets. E.g. calling rte_eth_rx_burst() with
> nb_pkts=64 only returns 32 packets.
>
>
> The API description of rte_eth_rx_burst() says:
>
> <quote>
> The rte_eth_rx_burst() function returns the number of packets actually
> retrieved, which is the number of rte_mbuf data structures effectively supplied
> into the rx_pkts array. A return value equal to nb_pkts indicates that the RX
> queue contained at least rx_pkts packets, and this is likely to signify that other
> received packets remain in the input queue. Applications implementing a
> "retrieve as much received packets as possible" policy can check this specific
> case and keep invoking the rte_eth_rx_burst() function until a value less than
> nb_pkts is returned.
> </quote>
>
> The driver implementation does not conform to the documented behavior for
> "retrieve as much received packets as possible" applications.
It seems not an issue, this function has comment bellow, it is design work in that way.
/*
* vPMD receive routine, only accept(nb_pkts >= RTE_IXGBE_DESCS_PER_LOOP)
*
* Notice:
* - nb_pkts < RTE_IXGBE_DESCS_PER_LOOP, just return no packet
* - nb_pkts > RTE_IXGBE_MAX_RX_BURST, only scan RTE_IXGBE_MAX_RX_BURST
* numbers of DD bit
* - floor align nb_pkts to a RTE_IXGBE_DESC_PER_LOOP power-of-two
*/
>
>
> Med venlig hilsen / kind regards
> - Morten Brørup
next prev parent reply other threads:[~2020-07-16 8:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-15 16:02 Morten Brørup
2020-07-16 8:49 ` Zhao1, Wei [this message]
2020-07-16 9:08 ` [dpdk-dev] ixgbe vector rx does not conform torte_eth_rx_burst() API Morten Brørup
2020-07-17 13:49 ` Bruce Richardson
2020-07-18 3:32 ` Zhao1, Wei
2020-07-18 3:44 ` Zhao1, Wei
2020-07-27 9:42 ` [dpdk-dev] ixgbe vector rx does not conform to rte_eth_rx_burst() API Morten Brørup
2020-07-27 10:35 ` Zhao1, Wei
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