[dpdk-dev] [PATCH v12 0/5] eal: add WC store functions

[Nicolau, Radu]

On 10/8/2020 8:28 AM, David Marchand wrote:
> On Wed, Sep 23, 2020 at 4:23 PM Radu Nicolau <radu.nicolau at intel.com> wrote:
>> Implement 2 new functions that will enable write combining
>> stores depending on architecture. The functions are provided
>> as a generic stub and a x86 specific implementation.
>>
>> The reason to implement these functions is to improve performance
>> by reducing the overhead associated with regular mmio writes when
>> updating the hardware queue tails and doorbells.
> For the record, on which CPU/platform was this tested and how much of
> an improvement did you get with this?

The improvement varies a lot with the particular usecase and the PMD, so 
it's difficult to state a number, but there were cases with performance 
improvements going well into the double digits, with very small bursts 
applications seeing the most benefits. Tests were done on a Snow Ridge 
platform.


>
> I did not see review/ack tokens from other arch maintainers, but since
> it has been on the ml for a while, I guess I can proceed as is.
>
>
>> With this patch set the I40E, ICE, IXGBE and QAT PMDs are updated to
>> use the write combining store functions with other PMDs to follow.
> This series will go through the main repo: copying Ferruh and Akhil for info.
>
>