On 9/21/2020 1:21 PM, Jakub Grajciar -X (jgrajcia - PANTHEON TECH SRO at
Cisco) wrote:
Using 'rte_mb' to synchronize the shared ring head/tail between
producer and consumer will stall the pipeline and damage
performance on the weak memory model platforms, such like aarch64.
Relax the expensive barrier with c11 atomic with explicit memory
ordering can improve 3.6% performance on throughput.
My question here is: `rte_mb` is supposed to make sure that head/tail
pointer are not updated before the packets are written into shared
memory.
Does the atomic ensures that the packets are written into shared
memory before head/tail pointers are updated?
Yes, it does.
The atomic store-release acts as a one-way barrier here to make sure all the
memory accesses before the store-release are observed before it.
Ok then, since the sync is there and the rest seems fine to me.
Thanks,
Jakub
Reviewed-by: Jakub Grajciar <jgraj...@cisco.com>
Applied to dpdk-next-net/main, thanks.
