From: Zhihong Wang <zhihong.wang@intel.com>
To: dev@dpdk.org
Cc: yuanhan.liu@linux.intel.com, bruce.richardson@intel.com,
john.mcnamara@intel.com, Zhihong Wang <zhihong.wang@intel.com>
Subject: [dpdk-dev] [PATCH v3] doc: virtio PMD Rx/Tx callbacks
Date: Thu, 30 Jun 2016 23:28:01 -0400 [thread overview]
Message-ID: <1467343681-91812-1-git-send-email-zhihong.wang@intel.com> (raw)
In-Reply-To: <1461210924-104947-1-git-send-email-zhihong.wang@intel.com>
This patch explains current virtio PMD Rx/Tx callbacks, to help understand
what's the difference, and how to enable the right ones.
Signed-off-by: Zhihong Wang <zhihong.wang@intel.com>
Acked-by: John McNamara <john.mcnamara@intel.com>
--------------
Changes in v3:
1. Rephrase for clearer description.
--------------
Changes in v2:
1. Changes on format and few descriptions.
---
doc/guides/nics/virtio.rst | 75 ++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 69 insertions(+), 6 deletions(-)
diff --git a/doc/guides/nics/virtio.rst b/doc/guides/nics/virtio.rst
index 06ca433..c6335d4 100644
--- a/doc/guides/nics/virtio.rst
+++ b/doc/guides/nics/virtio.rst
@@ -73,7 +73,7 @@ In this release, the virtio PMD driver provides the basic functionality of packe
* It supports multicast packets and promiscuous mode.
-* The descriptor number for the RX/TX queue is hard-coded to be 256 by qemu.
+* The descriptor number for the Rx/Tx queue is hard-coded to be 256 by qemu.
If given a different descriptor number by the upper application,
the virtio PMD generates a warning and fall back to the hard-coded value.
@@ -163,8 +163,9 @@ Host2VM communication example
which means received packets come from vEth0, and transmitted packets is sent to vEth0.
#. In the guest, bind the virtio device to the uio_pci_generic kernel module and start the forwarding application.
- When the virtio port in guest bursts rx, it is getting packets from the raw socket's receive queue.
- When the virtio port bursts tx, it is sending packet to the tx_q.
+ When the virtio port in guest bursts Rx, it is getting packets from the
+ raw socket's receive queue.
+ When the virtio port bursts Tx, it is sending packet to the tx_q.
.. code-block:: console
@@ -183,7 +184,9 @@ Host2VM communication example
The packet reception and transmission flow path is:
- IXIA packet generator->82599 PF->KNI rx queue->KNI raw socket queue->Guest VM virtio port 0 rx burst->Guest VM virtio port 0 tx burst-> KNI tx queue->82599 PF-> IXIA packet generator
+ IXIA packet generator->82599 PF->KNI Rx queue->KNI raw socket queue->Guest
+ VM virtio port 0 Rx burst->Guest VM virtio port 0 Tx burst-> KNI Tx queue
+ ->82599 PF-> IXIA packet generator
Virtio with qemu virtio Back End
--------------------------------
@@ -206,8 +209,68 @@ Virtio with qemu virtio Back End
In this example, the packet reception flow path is:
- IXIA packet generator->82599 PF->Linux Bridge->TAP0's socket queue-> Guest VM virtio port 0 rx burst-> Guest VM 82599 VF port1 tx burst-> IXIA packet generator
+ IXIA packet generator->82599 PF->Linux Bridge->TAP0's socket queue-> Guest
+ VM virtio port 0 Rx burst-> Guest VM 82599 VF port1 Tx burst-> IXIA packet
+ generator
The packet transmission flow is:
- IXIA packet generator-> Guest VM 82599 VF port1 rx burst-> Guest VM virtio port 0 tx burst-> tap -> Linux Bridge->82599 PF-> IXIA packet generator
+ IXIA packet generator-> Guest VM 82599 VF port1 Rx burst-> Guest VM virtio
+ port 0 Tx burst-> tap -> Linux Bridge->82599 PF-> IXIA packet generator
+
+
+Virtio PMD Rx/Tx Callbacks
+--------------------------
+
+Virtio driver has 3 Rx callbacks and 2 Tx callbacks.
+
+Rx callbacks:
+
+#. ``virtio_recv_pkts``:
+ Regular version without mergeable Rx buffer support.
+
+#. ``virtio_recv_mergeable_pkts``:
+ Regular version with mergeable Rx buffer support.
+
+#. ``virtio_recv_pkts_vec``:
+ Vector version without mergeable Rx buffer support, also fixes the available
+ ring indexes and uses vector instructions to optimize performance.
+
+Tx callbacks:
+
+#. ``virtio_xmit_pkts``:
+ Regular version.
+
+#. ``virtio_xmit_pkts_simple``:
+ Vector version fixes the available ring indexes to optimize performance.
+
+
+By default, the non-vector callbacks are used:
+
+* For Rx: If mergeable Rx buffers is disabled then ``virtio_recv_pkts`` is
+ used; otherwise ``virtio_recv_mergeable_pkts``.
+
+* For Tx: ``virtio_xmit_pkts``.
+
+
+Vector callbacks will be used when:
+
+* ``txq_flags`` is set to ``VIRTIO_SIMPLE_FLAGS`` (0xF01), which implies:
+
+ * Single segment is specified.
+
+ * No offload support is needed.
+
+* Mergeable Rx buffers is disabled.
+
+The corresponding callbacks are:
+
+* For Rx: ``virtio_recv_pkts_vec``.
+
+* For Tx: ``virtio_xmit_pkts_simple``.
+
+
+Example of using the vector version of the virtio poll mode driver in
+``testpmd``::
+
+ testpmd -c 0x7 -n 4 -- -i --txqflags=0xF01 --rxq=1 --txq=1 --nb-cores=1
--
2.5.0
next prev parent reply other threads:[~2016-07-01 10:33 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-21 3:55 [dpdk-dev] [PATCH] doc: virtio pmd versions Zhihong Wang
2016-06-09 12:35 ` Mcnamara, John
2016-06-09 12:52 ` Richardson, Bruce
2016-06-09 12:56 ` Mcnamara, John
2016-06-15 6:59 ` Wang, Zhihong
2016-06-14 23:53 ` [dpdk-dev] [PATCH v2] " Zhihong Wang
2016-06-24 16:03 ` Mcnamara, John
2016-06-29 3:27 ` Yuanhan Liu
2016-07-01 3:28 ` Zhihong Wang [this message]
2016-07-04 2:56 ` [dpdk-dev] [PATCH v3] doc: virtio PMD Rx/Tx callbacks Yuanhan Liu
2016-07-04 3:00 ` Wang, Zhihong
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1467343681-91812-1-git-send-email-zhihong.wang@intel.com \
--to=zhihong.wang@intel.com \
--cc=bruce.richardson@intel.com \
--cc=dev@dpdk.org \
--cc=john.mcnamara@intel.com \
--cc=yuanhan.liu@linux.intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).