Re: [dpdk-dev] [RFC] Add selection between vector and scalar mode in ixgbe

[Bruce Richardson <bruce.richardson@intel.com>]

On Tue, May 25, 2021 at 11:58:18AM +0500, Muhammad Ahmad wrote:
> 
> The selection between scalar mode and vector mode was removed for
> ixgbe driver in DPDK 20.02. The code base still has code
> for scalar mode but it cannot be selected at compile time. The
> vector mode is adequate for applications which require high
> throughput which is the case most of the time, but scalar mode has
> a use case in ultra-low-latency fintech applications for algorithmic
> trading. This use case was also presented at the DPDK userspace
> summit in September 2020.
> This patch enables the ability to select between scalar and vector
> modes for ixgbe drivers in the config.
> In the future we can introduce API in ehtdev, which allow user to
> select between latency and throughput mode.  
> 
> Signed-off-by: Muhammad Ahmad <muhammad.ahmad@emumba.com>
> ---
Rather than having compile-time selection, this should be supported via
runtime selection, using the force-max-simd-bitwidth flag. Setting the flag
to 64 should force scalar paths.

Regards,
/Bruce