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From: Morten Brørup <mb@smartsharesystems.com>
To: thomas@monjalon.net, ferruh.yigit@intel.com,
	arybchenko@solarflare.com, bruce.richardson@intel.com
Cc: jia.guo@intel.com, dev@dpdk.org,
	Morten Brørup <mb@smartsharesystems.com>
Subject: [dpdk-dev] [PATCH] ethdev: rte_eth_rx_burst() nb_pkts requirements
Date: Mon, 14 Sep 2020 13:05:11 +0200
Message-ID: <20200914110511.95609-1-mb@smartsharesystems.com> (raw)

Updated description of rte_eth_rx_burst() to reflect what drivers,
when using vector instructions, expect from nb_pkts.

Also discussed on the mailing list here:
http://inbox.dpdk.org/dev/98CBD80474FA8B44BF855DF32C47DC35C61257@smartserver.smartshare.dk/

Signed-off-by: Morten Brørup <mb@smartsharesystems.com>
---
 lib/librte_ethdev/rte_ethdev.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/librte_ethdev/rte_ethdev.h b/lib/librte_ethdev/rte_ethdev.h
index 70295d7ab..41f8ba4ef 100644
--- a/lib/librte_ethdev/rte_ethdev.h
+++ b/lib/librte_ethdev/rte_ethdev.h
@@ -4469,6 +4469,10 @@ int rte_eth_dev_hairpin_capability_get(uint16_t port_id,
  * burst-oriented optimizations in both synchronous and asynchronous
  * packet processing environments with no overhead in both cases.
  *
+ * @note
+ *   Some drivers using vector instructions require that *nb_pkts* is
+ *   divisible by 4 or 8, depending on the driver implementation.
+ *
  * The rte_eth_rx_burst() function does not provide any error
  * notification to avoid the corresponding overhead. As a hint, the
  * upper-level application might check the status of the device link once
@@ -4485,6 +4489,7 @@ int rte_eth_dev_hairpin_capability_get(uint16_t port_id,
  *   must be large enough to store *nb_pkts* pointers in it.
  * @param nb_pkts
  *   The maximum number of packets to retrieve.
+ *   The value must be divisible by 8 in order to work with any driver.
  * @return
  *   The number of packets actually retrieved, which is the number
  *   of pointers to *rte_mbuf* structures effectively supplied to the
-- 
2.17.1


             reply	other threads:[~2020-09-14 11:05 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-14 11:05 Morten Brørup [this message]
2020-09-14 11:26 ` Bruce Richardson
2020-09-14 12:42   ` [dpdk-dev] [PATCH] ethdev: rte_eth_rx_burst() nb_pktsrequirements Morten Brørup
2020-10-13 10:55     ` Ferruh Yigit
2020-10-14  8:26       ` [dpdk-dev] [PATCH] ethdev: rte_eth_rx_burst()nb_pktsrequirements Morten Brørup
2020-10-14  8:53         ` Thomas Monjalon
2020-10-14  9:29           ` Bruce Richardson
2020-10-14 11:14             ` Morten Brørup
2020-10-14 11:38               ` Bruce Richardson
2020-10-15  7:36                 ` Morten Brørup
2020-10-26 15:06                 ` [dpdk-dev] [PATCH] ethdev: rte_eth_rx_burst() nb_pkts requirements Morten Brørup
2020-10-26 15:15 ` Ajit Khaparde
2020-10-27 10:24 ` Bruce Richardson
2020-10-30  9:27   ` Ferruh Yigit

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