From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-2643-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Date: Wed, 1 Nov 2017 16:59:25 +0200 From: "Michael S. Tsirkin" Message-ID: <20171101162357-mutt-send-email-mst@kernel.org> References: <20171029125225.lx4ezpkbvjjsjv3x@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171029125225.lx4ezpkbvjjsjv3x@localhost.localdomain> Subject: [virtio-dev] Re: Virtio BoF minutes from KVM Forum 2017 To: Jens Freimann Cc: virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, virtio-comment@lists.oasis-open.org List-ID: On Sun, Oct 29, 2017 at 01:52:25PM +0100, Jens Freimann wrote: > Ilya: - you might have more completions than descriptors available > - partial descriptor chains are a problem for hardware because you might have > to read a bunch of conscriptors twice - how would you do deal with a big > buffer that cointains a large number of > small packets with respect to completions? > - is one bit for completion enough? right now it means descriptor was actually > used. how to we signal when it was completed? I am not sure I understand the difference. Under virtio, driver makes a descriptor available, then device reads/writes memory depending on descriptor type, then marks it as used. What does completed mean? > - concerned about not being able to do scatter/gatter with the ring layout. > Network drivers heavily using indirect buffers. - for a hardware > implementation a completion ring is a very convenient form for > some use cases, so we want an efficient implementation for them. If we had an > inline descriptor then a completion ring is just a normal ring and we won't > need another ring type. > - doesn't like the fact that we need to do a linear scan to find the length of > a descriptor chain. It would be nice if we could have the length of the chain > in the first descriptor (i.e. the number of chained descriptors, not the number > of posted descriptors which can be deduced from the id field) Not responding to rest of points since I don't understand the basic assumption above yet. -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org