[PATCH v3 1/7] eal: generic 64 bit counter

[Stephen Hemminger]

On Wed, 15 May 2024 11:30:45 +0200
Morten Brørup <mb at smartsharesystems.com> wrote:

> With a long term perspective, I consider this patch very useful.
> And its 32 bit implementation can be optimized for various architectures/compilers later.
> 
> 
> In addition, it would be "nice to have" if reset() and fetch() could be called from another thread than the thread adding to the counter.
> 
> As previously discussed [1], I think it can be done without significantly affecting fast path add() performance, by using an "offset" with Release-Consume ordering.
> 
> [1]: https://inbox.dpdk.org/dev/98CBD80474FA8B44BF855DF32C47DC35E9F427@smartserver.smartshare.dk/
> 


Without a specific driver use case, not sure why this added complexity is needed.
If there is a specific example, can add it later. Any atomic operation ends up
impacting the speculative execution pipeline on modern CPU's. This version
ends up being just a single add instruction on ARM and x86 64 bit.