Re: [dpdk-dev] [PATCH v2 2/9] net/hns3: support Tx push quick doorbell to improve perf

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 3/10/2021 6:16 AM, Min Hu (Connor) wrote:
> From: Chengwen Feng <fengchengwen@huawei.com>
> 
> Kunpeng 930 support Tx push mode which could improve performance, It
> works like below:
> 1. Add pcie bar45 which support driver direct write the Tx descriptor
> or tail reg to it.
> 2. Support three operations: a) direct write one Tx descriptor, b)
> direct write two Tx descriptors, c) direct write tail reg.
> 3. The original tail reg located at bar23, the above bar45 tail reg
> could provide better bandwidth from the hardware perspective.
> 
> The hns3 driver only support direct write tail reg (also have the name
> of quick doorbell), the detail:
> 1. Considering compatibility, firmware will report Tx push capa if the
> hardware support it.
> 2. Add control macro RTE_LIBRTE_HNS3_ENABLE_TX_PUSH which was not
> defined default.
> 3. If user define macro RTE_LIBRTE_HNS3_ENABLE_TX_PUSH and hardware
> support, then driver will direct write bar45 tail reg to inform the
> hardware.

Can you convert the copile time 'RTE_LIBRTE_HNS3_ENABLE_TX_PUSH' flag to runtime 
device argument?

There is already 'tx_push_enable' variable check on datapath, so converting to 
devarg shouldn't add any additional checks and shouldn't have performance impact.

> 
> Signed-off-by: Chengwen Feng <fengchengwen@huawei.com>
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>

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