On 3/23/2021 3:31 AM, fengchengwen wrote:
On 2021/3/22 21:58, Ferruh Yigit wrote:
On 3/19/2021 1:07 AM, Min Hu (Connor) wrote:
From: Chengwen Feng <fengcheng...@huawei.com>
Currently, the driver support multiple IO burst function and auto
selection of the most appropriate function based on offload
configuration.
Most applications such as l2fwd/l3fwd don't provide the means to
change offload configuration, so it will use the auto selection's io
burst function.
This patch support runtime config to select io burst function, which
add two config: rx_func_hint and tx_func_hint, both could assign
vec/sve/simple/common.
The driver will use the following rules to select io burst func:
a. if hint equal vec and meet the vec Rx/Tx usage condition then use
the neon function.
b. if hint equal sve and meet the sve Rx/Tx usage condition then use
the sve function.
c. if hint equal simple and meet the simple Rx/Tx usage condition then
use the simple function.
d. if hint equal common then use the common function.
e. if hint not set then:
e.1. if meet the vec Rx/Tx usage condition then use the neon function.
e.2. if meet the simple Rx/Tx usage condition then use the simple
function.
e.3. else use the common function.
Note: the sve Rx/Tx usage condition based on the vec Rx/Tx usage
condition and runtime environment (which must support SVE).
In the previous versions, driver will preferred use the sve function
when meet the sve Rx/Tx usage condition, but in this case driver could
get better performance if use the neon function.
Is this saying 'neon' is giving better performance even if 'sve' is supported?
I'm sorry to confuse you, let me explain the hns3 sve function history:
1. The sve instruction only support on our latest processor Kunpeng930, and
the sve Rx/Tx function is being gradually optimized.
2. We define a macro CONFIG_RTE_LIBRTE_HNS3_INC_VECTOR_SVE which equal n
default in the original scheme, so driver will not select sve Rx/Tx function
unless user config CONFIG_RTE_LIBRTE_HNS3_INC_VECTOR_SVE=y.
3. We plan to switch CONFIG_RTE_LIBRTE_HNS3_INC_VECTOR_SVE equal y when the
sve Rx/Tx function is fully optimized.
4. The makefile is switched to meson build in 20.11, and it's not recommended
to define the marco such as above, so the upload scheme is adjusted which
delete the macro CONFIG_RTE_LIBRTE_HNS3_INC_VECTOR_SVE, this leads to driver
select sve Rx/Tx function when meeting sve conditions (which are gcc support
compile sve and the host cpu&os support sve), but it doesn't fit out plan, so
here we modify it.
Got it, so you want keep the 'neon' path default until 'sve' path is more
optimized, thanks for clarification.
Signed-off-by: Chengwen Feng <fengcheng...@huawei.com>
Signed-off-by: Min Hu (Connor) <humi...@huawei.com>
---
v6:
- document hns3.rst about description of vec, common and simple.
---
doc/guides/nics/hns3.rst | 19 +++++++++
doc/guides/rel_notes/release_21_05.rst | 1 +
drivers/net/hns3/hns3_ethdev.c | 77
++++++++++++++++++++++++++++++++++
drivers/net/hns3/hns3_ethdev.h | 15 +++++++
drivers/net/hns3/hns3_ethdev_vf.c | 4 ++
drivers/net/hns3/hns3_rxtx.c | 54 +++++++++++++++++-------
6 files changed, 156 insertions(+), 14 deletions(-)
diff --git a/doc/guides/nics/hns3.rst b/doc/guides/nics/hns3.rst
index 84bd7a3..8f48240 100644
--- a/doc/guides/nics/hns3.rst
+++ b/doc/guides/nics/hns3.rst
@@ -46,6 +46,25 @@ Prerequisites
- Follow the DPDK :ref:`Getting Started Guide for Linux <linux_gsg>` to
setup the basic DPDK environment.
+Runtime Config Options
+----------------------
+
+- ``rx_func_hint`` (default ``none``)
+
+ Used to select Rx burst function, supported value are "vec", "sve", "simple",
"common".
``vec``, ``sve``, ``simple`` and ``common``. ??
+ When equal "vec" and meet the vector Rx usage condition then use the default
vector Rx implementation, 'neon' for Kunpeng Arm platform.
+ When equal "sve" and meet the sve Rx usage condition then use the sve Rx
function.
+ When equal "simple" and meet the simple Rx usage condition then use the
simple Rx function which indicates the Scalar algorithm obtained from
rte_eth_rx_burst_mode_get.
+ When equal "common" then use the common Rx function which indicates the
Scalar Scattered algorithm obtained from rte_eth_rx_burst_mode_get.
+
A few comments on the documentation,
- What about using `` to highlight the parameter, like ``vec``, on all
occurrences.
- What about adding bullet points for each parameter
- I think you can drop "When equal" start from all
- You can drop "obtained from rte_eth_rx_burst_mode_get" part, the function
name is not needed here, something like gives same information:
- Can "and meet the vector Rx usage condition" be simplified, overall what
about something like:
* ``simple``, if supported use the ``simple`` Rx function which indicates the
scalar algorithm.
- It is not clear what happens when provided parameter is not supported, like
when I set 'vec' but if PMD doesn't support it, which function will be
supported?
- Can you please try to limit the line length aroung 80 columns.
- No need to start words with uppercase for 'Scalar' & 'Scalar Scattered'
- Same for below Tx ones.
.
OK, will fix in later patch
