From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id 13E50A04C7; Tue, 26 Nov 2019 03:38:03 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 48AC22952; Tue, 26 Nov 2019 03:38:02 +0100 (CET) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id E4D4191 for ; Tue, 26 Nov 2019 03:37:59 +0100 (CET) X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Nov 2019 18:37:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,244,1571727600"; d="scan'208";a="383012735" Received: from yexl-server.sh.intel.com (HELO localhost) ([10.67.117.17]) by orsmga005.jf.intel.com with ESMTP; 25 Nov 2019 18:37:57 -0800 Date: Tue, 26 Nov 2019 10:34:07 +0800 From: Ye Xiaolong To: Yinan Cc: dev@dpdk.org, maxime.coquelin@redhat.com, tiwei.bie@intel.com, john.mcnamara@intel.com, zhihong.wang@intel.com Message-ID: <20191126023407.GF101220@intel.com> References: <20191126104238.40067-1-yinan.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191126104238.40067-1-yinan.wang@intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Subject: Re: [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi, yinan Minor nit, please use '--in-reply-to' when using git-send-email, it helps tracking all history about this patch together. Thanks, Xiaolong On 11/26, Yinan wrote: >From: Wang Yinan > >add virtio paths selection and usage introduction for better >virtio usability. > >Signed-off-by: Wang Yinan >--- > doc/guides/howto/index.rst | 1 + > .../virtio_paths_selection_and_usage.rst | 142 ++++++++++++++++++ > 2 files changed, 143 insertions(+) > create mode 100644 doc/guides/howto/virtio_paths_selection_and_usage.rst > >diff --git a/doc/guides/howto/index.rst b/doc/guides/howto/index.rst >index a4c131652..6edb8d5be 100644 >--- a/doc/guides/howto/index.rst >+++ b/doc/guides/howto/index.rst >@@ -16,6 +16,7 @@ HowTo Guides > vfd > virtio_user_for_container_networking > virtio_user_as_exceptional_path >+ virtio_paths_selection_and_usage > packet_capture_framework > telemetry > debug_troubleshoot >diff --git a/doc/guides/howto/virtio_paths_selection_and_usage.rst b/doc/guides/howto/virtio_paths_selection_and_usage.rst >new file mode 100644 >index 000000000..bfd933fac >--- /dev/null >+++ b/doc/guides/howto/virtio_paths_selection_and_usage.rst >@@ -0,0 +1,142 @@ >+.. SPDX-License-Identifier: BSD-3-Clause >+ Copyright(c) 2019 Intel Corporation. >+ >+Virtio paths Selection and Usage >+================================ >+ >+Logically virtio-PMD has 9 paths based on the combination of virtio features >+(Rx mergeable, In-order, Packed virtqueue), below is an introduction of virtio >+common features: >+ >+* `Rx mergeable + virtio-v1.1-cs01.html#x1-700009>`_: With this feature negotiated, device >+ can receive larger packets by combining individual descriptors. >+* `In-order + virtio-v1.1-cs01.html#x1-690008>`_: Some devices always use descriptors >+ in the same order in which they have been made available, these >+ devices can offer the VIRTIO_F_IN_ORDER feature. If this feature negotiated, >+ driver will use descriptors in order. Meanwhile, this knowledge allows device >+ operate used ring in batches and driver operate available ring in batches and >+ such can decrease cache miss rate. >+* `Packed virtqueue + virtio-v1.1-cs01.html#x1-610007>`_: The structure of packed virtqueue is >+ different from split virtqueue, split virtqueue is composed of available ring, >+ used ring and descriptor table, while packed virtqueue is composed of descriptor >+ ring, driver event suppression and device event suppression. The idea behind >+ this is to improve performance by avoiding cache misses and and make it easier >+ for devices to implement. >+ >+Virtio paths Selection >+---------------------- >+ >+If packed virtqueue is not negotiated, below split virtqueue paths can be selected >+according to below configuration: >+ >+#. Split virtqueue mergeable path: If Rx mergeable is negotiated, in-order feature is >+ not negotiated, this path will be selected. >+#. Split virtqueue non-mergeable path: If Rx mergeable and in-order feature are not >+ negotiated, also Rx offload(s) are requested, this path can be selected. >+#. Split virtqueue in-order mergeable path: If in-order feature and Rx mergeable are >+ both negotiated, this path can be selected. >+#. Split virtqueue in-order non-mergeable path: If in-order feature is negotiated and >+ Rx mergeable is not negotiated, this path can be selected. >+#. Split virtqueue vectorized RX path: If Rx mergeable is disabled and no Rx offload >+ requested, this path can be selected. >+ >+If packed virtqueue is negotiated, below packed virtqueue paths can be selected >+according to below configuration: >+ >+#. Packed virtqueue mergeable path: If Rx mergeable is negotiated, in-order feature >+ is not negotiated, this path will be selected. >+#. Packed virtqueue non-mergeable path: If Rx mergeable and in-order feature are not >+ negotiated, also Rx offload(s) are requested, this path will be selected. >+#. Packed virtqueue in-order mergeable path: If in-order feature and Rx mergeable are >+ both negotiated, this path will be selected. >+#. Packed virtqueue in-order non-mergeable path: If in-order feature is negotiated and >+ Rx mergeable is not negotiated, this path will be selected. >+ >+Rx/Tx callbacks of each Virtio path >+----------------------------------- >+ >+Refer to above descriptions, virtio path and Rx/TX callbacks are auto selected by >+different parameters of vdev and workloads. Rx callbacks and Tx callbacks name for >+each Virtio Path are shown in following tables:: >+ >+ +----------------------------------------------------------------------------------------------------------+ >+ | Virtio path | Rx callbacks | TX callbacks | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue mergeable path |virtio_recv_mergeable_pkts | virtio_xmit_pkts | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue non-mergeable path | virtio_recv_pkts | virtio_xmit_pkts | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue in-order mergeable path | virtio_recv_pkts_inorder | virtio_xmit_pkts_inorder| >+ +----------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue in-order non-mergeable path | virtio_recv_pkts_inorder | virtio_xmit_pkts_inorder| >+ +----------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue vectorized RX path | virtio_recv_pkts_vec | virtio_xmit_pkts | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue mergeable path | virtio_recv_mergeable_pkts_packed| virtio_xmit_pkts_packed | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue normal path | virtio_recv_pkts_packed | virtio_xmit_pkts_packed | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue in-order mergeable path | virtio_recv_mergeable_pkts_packed| virtio_xmit_pkts_packed | >+ +----------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue in-order normal path | virtio_recv_pkts_packed | virtio_xmit_pkts_packed | >+ +----------------------------------------------------------------------------------------------------------+ >+ >+Virtio paths Support Status from Release to Release >+--------------------------------------------------- >+ >+Virtio feature implementation: >+ >+* In-order feature implemented in DPDK 18.08 by adding new Rx/TX callbacks >+ ``virtio_recv_pkts_inorder`` and ``virtio_xmit_pkts_inorder``. >+* Packed virtqueue implemented in DPDK 19.02 by adding new Rx/TX callbacks >+ ``virtio_recv_pkts_packed`` , ``virtio_recv_mergeable_pkts_packed`` and >+ ``virtio_xmit_pkts_packed``. >+ >+Virtio path number changes from release to release, all virtio paths support >+status are shown in below table:: >+ >+ +--------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Virtio path\ DPDK version | v16.11 | v17.02 | v17.05 | v17.08 | v17.11 | v18.02 | v18.05 | v18.08 | v18.11 | v19.02 | v19.05 | v19.08 | >+ +--------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue mergebale path | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | >+ +--------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue non-mergeable path | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | >+ +--------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue vectorized RX path | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue simple TX path | Y | Y | Y | Y | Y | Y | Y | N | N | N | N | N | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue in-order non-mergeable path | | | | | | | | Y | Y | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Split virtqueue in-order mergeable path | | | | | | | | Y | Y | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue mergeable path | | | | | | | | | | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue non-mergeable path | | | | | | | | | | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue in-order mergeable path | | | | | | | | | | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ |Packed virtqueue in-order non-mergeable path| | | | | | | | | | Y | Y | Y | >+ ---------------------------------------------------------------------------------------------------------------------------------------------------------+ >+ >+QEMU Support Status >+------------------- >+ >+* Qemu now support three paths of split virtqueue: Split virtqueue mergebale path, >+ Split virtqueue no-mergeable path, Split virtqueue vectorized RX path. >+* Since qemu 4.2.0, Packed virtqueue mergeable path and Packed virtqueue non-mergeable >+ path can be supported. >+ >+How to Debug >+------------ >+ >+If you meet performance drop or some other issues after upgrading the driver >+or configuration, below steps can help you identify which path you selected and >+root cause faster. >+ >+#. Run vhost/virtio test case; >+#. Run "perf top" and check virtio Rx/tx callback names; >+#. Identify which virtio path is selected refer to above table. >-- >2.17.1 >