* [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection
@ 2019-11-26 10:42 Yinan
2019-11-26 2:34 ` Ye Xiaolong
2019-11-26 3:02 ` Tiwei Bie
0 siblings, 2 replies; 3+ messages in thread
From: Yinan @ 2019-11-26 10:42 UTC (permalink / raw)
To: dev, maxime.coquelin, tiwei.bie; +Cc: john.mcnamara, zhihong.wang, Wang Yinan
From: Wang Yinan <yinan.wang@intel.com>
add virtio paths selection and usage introduction for better
virtio usability.
Signed-off-by: Wang Yinan <yinan.wang@intel.com>
---
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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ virtio-v1.1-cs01.html#x1-700009>`_: With this feature negotiated, device
+ can receive larger packets by combining individual descriptors.
+* `In-order <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ 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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
+ 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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection
2019-11-26 10:42 [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection Yinan
@ 2019-11-26 2:34 ` Ye Xiaolong
2019-11-26 3:02 ` Tiwei Bie
1 sibling, 0 replies; 3+ messages in thread
From: Ye Xiaolong @ 2019-11-26 2:34 UTC (permalink / raw)
To: Yinan; +Cc: dev, maxime.coquelin, tiwei.bie, john.mcnamara, zhihong.wang
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 <yinan.wang@intel.com>
>
>add virtio paths selection and usage introduction for better
>virtio usability.
>
>Signed-off-by: Wang Yinan <yinan.wang@intel.com>
>---
> 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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
>+ virtio-v1.1-cs01.html#x1-700009>`_: With this feature negotiated, device
>+ can receive larger packets by combining individual descriptors.
>+* `In-order <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
>+ 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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
>+ 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection
2019-11-26 10:42 [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection Yinan
2019-11-26 2:34 ` Ye Xiaolong
@ 2019-11-26 3:02 ` Tiwei Bie
1 sibling, 0 replies; 3+ messages in thread
From: Tiwei Bie @ 2019-11-26 3:02 UTC (permalink / raw)
To: Yinan; +Cc: dev, maxime.coquelin, john.mcnamara, zhihong.wang
Hi Yinan,
Thanks for the work! Will take a closer look ASAP.
Please see some quick comments inline.
On Tue, Nov 26, 2019 at 05:42:38AM -0500, Yinan wrote:
> From: Wang Yinan <yinan.wang@intel.com>
>
> add virtio paths selection and usage introduction for better
> virtio usability.
>
> Signed-off-by: Wang Yinan <yinan.wang@intel.com>
> ---
When sending new versions, please use --in-reply-to [1].
And it would be better if you can add a brief changelog.
[1] https://core.dpdk.org/contribute/#send
> 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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
> + virtio-v1.1-cs01.html#x1-700009>`_: With this feature negotiated, device
Instead of referring to "Multi-buffer requests", below section is
more related:
https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/virtio-v1.1-cs01.html#x1-2140004
> + can receive larger packets by combining individual descriptors.
> +* `In-order <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
> + 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 <https://docs.oasis-open.org/virtio/virtio/v1.1/cs01/
> + 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.
s/can be/will be/
This applies to other similar cases as well.
> +#. 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.
Currently, requesting Rx offload or not doesn't matter in this case.
> +#. 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 |
s/mergebale/mergeable/
> + +--------------------------------------------------------------------------------------------------------------------------------------------------------+
> + |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,
s/support/supports/
s/mergebale/mergeable/
> + Split virtqueue no-mergeable path, Split virtqueue vectorized RX path.
s/no-mergeable/non-mergeable/
> +* 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2019-11-26 3:02 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-11-26 10:42 [dpdk-dev] [PATCH v3] doc: clarify virtio PMD path selection Yinan
2019-11-26 2:34 ` Ye Xiaolong
2019-11-26 3:02 ` Tiwei Bie
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).