From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: virtio-dev-return-7552-cohuck=redhat.com@lists.oasis-open.org Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 7AB78985E7E for ; Wed, 15 Jul 2020 15:47:40 +0000 (UTC) Date: Wed, 15 Jul 2020 16:47:32 +0100 From: Stefan Hajnoczi Message-ID: <20200715154732.GC47883@stefanha-x1.localdomain> References: <87r1tdydpz.fsf@linaro.org> <20200715114855.GF18817@stefanha-x1.localdomain> <877dv4ykin.fsf@linaro.org> MIME-Version: 1.0 In-Reply-To: <877dv4ykin.fsf@linaro.org> Subject: Re: [virtio-dev] On doorbells (queue notifications) Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="5/uDoXvLw7AC5HRs" Content-Disposition: inline To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: virtio-dev@lists.oasis-open.org, Zha Bin , Jing Liu , Chao Peng , cohuck@redhat.com List-ID: --5/uDoXvLw7AC5HRs Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jul 15, 2020 at 02:29:04PM +0100, Alex Benn=E9e wrote: > Stefan Hajnoczi writes: > > On Tue, Jul 14, 2020 at 10:43:36PM +0100, Alex Benn=E9e wrote: > >> Finally I'm curious if this is just a problem avoided by the s390 > >> channel approach? Does the use of messages over a channel just avoid t= he > >> sort of bouncing back and forth that other hypervisors have to do when > >> emulating a device? > > > > What does "bouncing back and forth" mean exactly? >=20 > Context switching between guest and hypervisor. I have CCed Cornelia Huck, who can explain the lifecycle of an I/O request on s390 channel I/O. Stefan --5/uDoXvLw7AC5HRs Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhpWov9P5fNqsNXdanKSrs4Grc8gFAl8PJRQACgkQnKSrs4Gr c8izhgf/XKIEHNxlhuYFC3NxAcu27JsTuZrxdWggjjObKrVGhwo/fTZNcJhpBrl1 nAE3oBk5eSdZmYv/nvjkfq7ZXC6+MCKngCyZVGxNe8KzkZeGpekzmStTcGhPx5+u MyChEDkAQdr0vh6xCIY/qxos1nSRcLOp+DzVthD8La68Hl5tB7gLKR3oJe7H34Qm 8IHW790mHOJ7qTssH6YzKYqRp8kzfWLtXZTqRab5ID5LlPHuXrQMJvMxC6Nf7Tah SWnINOftj0x9Y6L1X8mVQV6r2/nQZRalMsJ24sL3lmQfr9+TTNqpV148VWB96UNQ 9jSLfEKZBs/vxSlYCx4HwzxI+71Yvg== =3kE0 -----END PGP SIGNATURE----- --5/uDoXvLw7AC5HRs--