Re: [Linuxarm] Re: [RFC v2] net: sched: implement TCQ_F_CAN_BYPASS for lockless qdisc

On Thu, Mar 18, 2021 at 1:33 AM Yunsheng Lin [off-list ref] wrote:

quoted

That offer definitely still stands. Generalization sounds like a lot of fun.

Keep in mind though that it's an eventually consistent queue, not an
immediately consistent one, so that might not match all use cases. It
works with wg because we always trigger the reader thread anew when it
finishes, but that doesn't apply to everyone's queueing setup.

Thanks for mentioning this.

"multi-producer, single-consumer" seems to match the lockless qdisc's
paradigm too, for now concurrent enqueuing/dequeuing to the pfifo_fast's
queues() is not allowed, it is protected by producer_lock or consumer_lock.

The other thing is that if you've got memory for a ring buffer rather
than a list queue, we worked on an MPMC ring structure for WireGuard a
few years ago that we didn't wind up using in the end, but it lives
here:
https://git.zx2c4.com/wireguard-monolithic-historical/tree/src/mpmc_ptr_ring.h?h=tg/mpmc-benchmark