On Wed, 24 Feb 2021 15:20:13 -0600 Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> wrote:
> rte_eal_remote_launch and rte_eal_wait_lcore need to provide > correct memory ordering to address the data communication from > main core to worker core and vice versa. > > There are 2 use cases: > 1) All the store operations (meant for worker) by main core > should be visible to worker core before the worker core runs the > assigned function > > 2) All the store operations by the worker core should be visible > to the main core after rte_eal_wait_lcore returns. > > For the data that needs to be communicated to the worker after > the rte_eal_remote_launch returns, load-acquire and store-release > semantics should be used (just like any other writer-reader use case). > > For the main to worker communication, the pointer to function > to execute is used as the guard variable. Hence, resetting of > the function pointer is important. > > For the worker to main communication, the existing code uses the > lcore state as the guard variable. However, it looks like > the FINISHED state is not really required. Hence the FINISHED state > is removed before using the state as the guard variable. I would like > some feedback on why the FINISHED state is required. I have not > paid attention to what it means for backward compatibility. > If it is decided to remove this state, documentation changes are > required. > Most likely all use of volatile in DPDK is suspect. Perhaps we should re-enable the "volatile considered harmful" warning in checkpatch
