On 2020-11-16 09:10, Xuan Zhuo wrote:
When we write all cq items to tx, we have to wait for a new event based on poll to indicate that it is writable. But the current writability is triggered based on whether tx is full or not, and In fact, when tx is dissatisfied, the user of cq's item may not necessarily get it, because it may still be occupied by the network card. In this case, we need to know when cq is available, so this patch adds a socket option, When the user configures this option using setsockopt, when cq is available, a readable event is generated for all xsk bound to this umem. I can't find a better description of this event, I think it can also be 'readable', although it is indeed different from the 'readable' of the new data. But the overhead of xsk checking whether cq or rx is readable is small. Signed-off-by: Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx>
Thanks for the patch! I'm not a fan of having two different "readable" event (both Rx and cq). Could you explain a bit what the use case is, so I get a better understanding. The Tx queues has a back-pressure mechanism, determined of the number of elements in cq. Is it related to that? Please explain a bit more what you're trying to solve, and maybe we can figure out a better way forward! Thanks! Björn
