From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [RFC v4 3/5] virtio_ring: add packed ring support Date: Mon, 21 May 2018 10:30:51 +0800 Message-ID: References: <20180516123909.GB986@debian> <20180516134550.GB4171@debian> <20180516143332.GA1957@debian> <20180518112950.GA28224@debian> <20180518143334.GA4537@debian> <1a661df0-8ca9-b31d-9c17-8684d608a33a@redhat.com> <20180519022938.GA18888@debian> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: mst@redhat.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, wexu@redhat.com, jfreimann@redhat.com To: Tiwei Bie Return-path: In-Reply-To: <20180519022938.GA18888@debian> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018年05月19日 10:29, Tiwei Bie wrote: >> I don't hope so. >> >>> I agreed driver should track the DMA addrs or some >>> other necessary things from the very beginning. And >>> I also repeated the spec to emphasize that it does >>> make sense. And I'd like to do that. >>> >>> What I was saying is that, to support OOO, we may >>> need to manage these context (which saves DMA addrs >>> etc) via a list which is similar to the desc list >>> maintained via `next` in split ring instead of an >>> array whose elements always can be indexed directly. >> My point is these context is a must (not only for OOO). > Yeah, and I have the exactly same point after you > pointed that I shouldn't get the addrs from descs. > I do think it makes sense. I'll do it in the next > version. I don't have any doubt about it. All my > questions are about the OOO, instead of whether we > should save context or not. It just seems that you > thought I don't want to do it, and were trying to > convince me that I should do it. Right, but looks like I was wrong :) > >>> The desc ring in split ring is an array, but its >>> free entries are managed as list via next. I was >>> just wondering, do we want to manage such a list >>> because of OOO. It's just a very simple question >>> that I want to hear your opinion... (It doesn't >>> means anything, e.g. It doesn't mean I don't want >>> to support OOO. It's just a simple question...) >> So the question is yes. But I admit I don't have better idea other than what >> you propose here (something like split ring which is a little bit sad). >> Maybe Michael had. > Yeah, that's why I asked this question. It will > make the packed ring a bit similar to split ring > at least in the driver part. So I want to draw > your attention on this to make sure that we're > on the same page. Yes. I think we are. Thanks > Best regards, > Tiwei Bie >