From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:46985) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZfTtX-0002vN-Ot for qemu-devel@nongnu.org; Fri, 25 Sep 2015 10:22:40 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZfTtW-0007ZU-VO for qemu-devel@nongnu.org; Fri, 25 Sep 2015 10:22:39 -0400 References: <1443188504-20296-1-git-send-email-berto@igalia.com> From: Eric Blake Message-ID: <560558A2.3020804@redhat.com> Date: Fri, 25 Sep 2015 08:22:26 -0600 MIME-Version: 1.0 In-Reply-To: <1443188504-20296-1-git-send-email-berto@igalia.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="JmE3grb0FGdgkfwfop3faURGVoeciwaI9" Subject: Re: [Qemu-devel] [PATCH] block: disable I/O limits at the beginning of bdrv_close() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alberto Garcia , qemu-devel@nongnu.org Cc: Kevin Wolf , qemu-block@nongnu.org, Stefan Hajnoczi , Max Reitz This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --JmE3grb0FGdgkfwfop3faURGVoeciwaI9 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 09/25/2015 07:41 AM, Alberto Garcia wrote: > Disabling I/O limits from a BDS also drains all pending throttled > requests, so it should be done at the beginning of bdrv_close() with > the rest of the bdrv_drain() calls before the BlockDriver is closed. Can this be abused? If I have a guest running in a cloud where the cloud provider has put severe throttling limits on me, but lets me hotplug to my heart's content, couldn't I just repeatedly plug/unplug the disk to get around the throttling (every time I unplug, all writes flush at full speed, then I immediately replug to start batching up a new set of writes). In other words, shouldn't the draining still be throttled, to prevent my abuse? --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --JmE3grb0FGdgkfwfop3faURGVoeciwaI9 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJWBViiAAoJEKeha0olJ0NqOEEH/jI4VY5qMa84u2mkQCJxaYEF a5I5GJ/F5Nb1K+PlMdJAlkLZgu09cv+P2UL3U+NOlLMt4L0Om6BYMqJiXsW69s+8 vOxmjco7ZvYuNsIbOkrToUKxNOYsCRWBFa/MrA8N+rfMtxZ4PjV7a5xeImPXtRqa F3FOSNa36nE4l9Kn7TSPv6bWaFXabxCkoKX3U1BMEBkeXWlzyyleA3Wkypzk6IIX GQs+GTyVZp4Yk8SCXN+6BN+adEwiT/vLa54bdS26J18W902L5EIfxxDzyytNdxpa pWv81lZMx4IAI4B9kxBXPkXAQyggkrKcIVMwSe3IURHSGKLNjv0KqqxbOFhM8FQ= =LXhU -----END PGP SIGNATURE----- --JmE3grb0FGdgkfwfop3faURGVoeciwaI9--