On Tue, Jun 18, 2024 at 08:52:38AM +0800, Jason Wang wrote: > On Mon, Jun 17, 2024 at 5:30 PM Jiri Pirko <jiri@xxxxxxxxxxx> wrote: > > > > Mon, Jun 17, 2024 at 03:44:55AM CEST, jasowang@xxxxxxxxxx wrote: > > >On Mon, Jun 10, 2024 at 10:19 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > > >> > > >> On Fri, Jun 07, 2024 at 01:30:34PM +0200, Jiri Pirko wrote: > > >> > Fri, Jun 07, 2024 at 12:23:37PM CEST, mst@xxxxxxxxxx wrote: > > >> > >On Fri, Jun 07, 2024 at 11:57:37AM +0200, Jiri Pirko wrote: > > >> > >> >True. Personally, I would like to just drop orphan mode. But I'm not > > >> > >> >sure others are happy with this. > > >> > >> > > >> > >> How about to do it other way around. I will take a stab at sending patch > > >> > >> removing it. If anyone is against and has solid data to prove orphan > > >> > >> mode is needed, let them provide those. > > >> > > > > >> > >Break it with no warning and see if anyone complains? > > >> > > > >> > This is now what I suggested at all. > > >> > > > >> > >No, this is not how we handle userspace compatibility, normally. > > >> > > > >> > Sure. > > >> > > > >> > Again: > > >> > > > >> > I would send orphan removal patch containing: > > >> > 1) no module options removal. Warn if someone sets it up > > >> > 2) module option to disable napi is ignored > > >> > 3) orphan mode is removed from code > > >> > > > >> > There is no breakage. Only, hypotetically performance downgrade in some > > >> > hypotetical usecase nobody knows of. > > >> > > >> Performance is why people use virtio. It's as much a breakage as any > > >> other bug. The main difference is, with other types of breakage, they > > >> are typically binary and we can not tolerate them at all. A tiny, > > >> negligeable performance regression might be tolarable if it brings > > >> other benefits. I very much doubt avoiding interrupts is > > >> negligeable though. And making code simpler isn't a big benefit, > > >> users do not care. > > > > > >It's not just making code simpler. As discussed in the past, it also > > >fixes real bugs. > > > > > >> > > >> > My point was, if someone presents > > >> > solid data to prove orphan is needed during the patch review, let's toss > > >> > out the patch. > > >> > > > >> > Makes sense? > > >> > > >> It's not hypothetical - if anything, it's hypothetical that performance > > >> does not regress. And we just got a report from users that see a > > >> regression without. So, not really. > > > > > >Probably, but do we need to define a bar here? Looking at git history, > > >we didn't ask a full benchmark for a lot of commits that may touch > > > > Moreover, there is no "benchmark" to run anyway, is it? > > Yes, so my point is to have some agreement on > > 1) what kind of test needs to be run for a patch like this. > 2) what numbers are ok or not > > Thanks That's a $1mln question and the difficulty is why we don't change behaviour drastically for users without a fallback even if we think we did a bunch of testing. > > > > > > >performance. > > > > > >Thanks > > > > > >> > > >> > > > >> > > > > >> > >-- > > >> > >MST > > >> > > > > >> > > > > >
