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Tsirkin" To: Jiri Pirko Cc: Jason Wang , Jason Xing , Heng Qi , davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, xuanzhuo@linux.alibaba.com, virtualization@lists.linux.dev, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, netdev@vger.kernel.org Subject: Re: [patch net-next] virtio_net: add support for Byte Queue Limits Message-ID: <20240610101346-mutt-send-email-mst@kernel.org> References: <20240606020248-mutt-send-email-mst@kernel.org> <20240607062231-mutt-send-email-mst@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Jun 07, 2024 at 01:30:34PM +0200, Jiri Pirko wrote: > Fri, Jun 07, 2024 at 12:23:37PM CEST, mst@redhat.com 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. > 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. > > > > >-- > >MST > >