[dpdk-dev] [RFC v5] /net: memory interface (memif)

[Damjan Marion (damarion)]

> On 6 May 2019, at 13:00, Jakub Grajciar -X (jgrajcia - PANTHEON TECHNOLOGIES at Cisco) <jgrajcia at cisco.com> wrote:
> 
> 
> ________________________________________
> From: Honnappa Nagarahalli <Honnappa.Nagarahalli at arm.com>
> Sent: Friday, May 3, 2019 6:27 AM
> To: Jakub Grajciar; Ferruh Yigit; dev at dpdk.org; Honnappa Nagarahalli
> Cc: nd; nd
> Subject: RE: [dpdk-dev] [RFC v5] /net: memory interface (memif)
> 
>> On 3/22/2019 11:57 AM, Jakub Grajciar wrote:
>>> Memory interface (memif), provides high performance packet transfer
>>> over shared memory.
>>> 
>>> Signed-off-by: Jakub Grajciar <jgrajcia at cisco.com>
>> 
> 
> <...>
> 
>>    With that in mind, I believe that 23Mpps is fine performance. No
>> performance target is
>>    defined, the goal is to be as fast as possible.
> Use of C11 atomics have proven to provide better performance on weakly ordered architectures (at least on Arm). IMO, C11 atomics should be used to implement the fast path functions at least. This ensures optimal performance on all supported architectures in DPDK.
> 
>    Atomics are not required by memif driver.

Correct, only thing we need is store barrier once per batch of packets,
to make sure that descriptor changes are globally visible before we bump head pointer.

-- 
Damjan