From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36317) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1df4qK-00037m-VQ for qemu-devel@nongnu.org; Tue, 08 Aug 2017 09:46:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1df4qF-0003zl-VB for qemu-devel@nongnu.org; Tue, 08 Aug 2017 09:46:45 -0400 Date: Tue, 8 Aug 2017 16:45:44 +0300 From: Manos Pitsidianakis Message-ID: <20170808134544.paekftiounmirhbo@postretch> References: <20170731095443.28211-1-el13635@mail.ntua.gr> <20170731095443.28211-6-el13635@mail.ntua.gr> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="gaxekyluahptihdx" Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH v3 5/7] block: add throttle block filter driver List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia Cc: qemu-devel , Kevin Wolf , Stefan Hajnoczi , qemu-block --gaxekyluahptihdx Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 08, 2017 at 03:13:36PM +0200, Alberto Garcia wrote: >On Mon 31 Jul 2017 11:54:41 AM CEST, Manos Pitsidianakis wrote: >> block/throttle.c uses existing I/O throttle infrastructure inside a >> block filter driver. I/O operations are intercepted in the filter's >> read/write coroutines, and referred to block/throttle-groups.c >> >> The driver can be used with the syntax >> -drive driver=3Dthrottle,file.filename=3Dfoo.qcow2, \ >> limits.iops-total=3D...,throttle-group=3Dbar > >Sorry for not having noticed this earlier, but can't you define the >throttling group (and its limits) using -object throttle-group ... as >shown in the previous patch, and simply reference it here? Or would we >have two alternative ways of setting the throttling limits? > >What happens if you have many -drive lines each one with a different set >of limits but with the same throttling group? The limits of the last one to be processed will win. Quoting a reply I=20 made to Kevin on the interface test patch: >> You're right, I missed this. The test result shows that this command >> succeeds. Do we really want to allow other nodes to be affected with a >> blockdev-add? Wouldn't it be cleaner to just forbid the combination of >> limits and throtte-group? > >So basically only anonymous, immutable groups can be created through the= =20 >driver then. All other shared group configurations must be explicitly=20 >created with an -object / object-add syntax. I think this is a neat=20 >separation and compromise if we allow anonymous groups. If not, we can=20 >ignore limits on the throttle driver. So basically if we have anonymous groups, we accept limits in the driver=20 options but only without a group-name. Without anonymous groups, we=20 remove limits from the driver options and only use the=20 object-add/-object commands to create throttle groups. Does this sound=20 like a good idea? It will be more verbose for the human user. One=20 advantage: all throttle groups can then be managed through=20 qom-set/qom-get since they are owned by the qom tree. --gaxekyluahptihdx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEvy2VxhCrsoeMN1aIc2J8L2kN9xAFAlmJwIgACgkQc2J8L2kN 9xBUag/+PssQhcKSQnAotJQGaL+LX9EWjsxx+uOa5WBayYMMQ5R+pAP/4CuMrvDV RtEZdt1Pbp+hc5IcTCp8vbIc7iC8tVV0eVn+dzWnjI5yXEqTzyLqgoyVCbQ1MLVX buDyLLHI3nofYgHnPsVtI8XuwUQIp56aQ/Pu/PsAtD5fiS8YdmNtI666wQ+Vwj/9 b+J5pO50BtIrh4v4z18a8DyqMzsdGmzBF+egWakMFmFniOFAV6nRZD8p8bGhotkY +wT/xko2oqlyds8nZeINh1ciO2/URwi9bX8trVhBlhoZdZ6WKjkCz0+4213bCjgR 2bi/23hfJbGKXdKB+w2xUuMZTtShzemB8hG2+7RbcqCsaNuLDTslxqL4wZeNO9GV fOdHElmbMhgIJTkETzTF5ktudkzyJlk+1sLbxa8cOCFWS6T2pmmKVGYItbtolbEq KHDEzXZzN8jGoT869PseVwj4Nkrx7MaKGQ0t8tR0C1B4spMtQ33LL0Hs8JgjE7cZ s9b1z/rYWxnXAtXy7Qsa3f7Qh2LmvPOSLHKwSr09XzJAVNDaCNWMD1zJkB9Y1SY3 g5LlW3KBXdXmWHguAUVhWiVT+XRWuwUlSGTE15+9MBALnXgwIytMJkGP+Ukm1oqB IkLj9wDXn82ic6qWePlnrdC5ZNkOV4/NFtHKBQN+vtdqiKXRlZQ= =5BWh -----END PGP SIGNATURE----- --gaxekyluahptihdx--