From: "Michael S. Tsirkin" <m...@redhat.com> Date: Fri, 16 Feb 2018 09:40:54 +0200
> So pointer rings work fine, but they have a problem: > make them too small and not enough entries fit. > Make them too large and you start flushing your cache > and running out of memory. > > This is a new idea of mine: a ring backed by a > linked list. Once you run out of rin entries, > instead of a drop you fall back on a list with > a common lock. > > Should work well for the case where the ring is typically sized > correctly, but will help address the fact that some user try to set e.g. > tx queue length to 1000000. > > My hope this will move us closer to direction where e.g. fw codel can > use ptr rings without locking at all. > The API is still very rough, and I really need to take a hard look > at lock nesting. > > Completely untested, sending for early feedback/flames. > > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> So the idea is that if a user sets a really huge TX queue length, we allocate a ptr_ring which is smaller, and use the backup linked list when necessary to provide the requested TX queue length legitimately. Right?
