From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42634) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VlJh3-0003sf-5A for qemu-devel@nongnu.org; Tue, 26 Nov 2013 09:32:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VlJgw-00004y-UU for qemu-devel@nongnu.org; Tue, 26 Nov 2013 09:32:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:11367) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VlJgw-00004t-ME for qemu-devel@nongnu.org; Tue, 26 Nov 2013 09:32:42 -0500 Message-ID: <5294B105.2080000@redhat.com> Date: Tue, 26 Nov 2013 07:32:37 -0700 From: Eric Blake MIME-Version: 1.0 References: <1385473433-15844-1-git-send-email-akong@redhat.com> <5294A902.5060000@redhat.com> In-Reply-To: <5294A902.5060000@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="pbMJXDpHICemVFNUH5IoV1KgPJQAg4KF4" Subject: Re: [Qemu-devel] [PATCH] virtio-rng: correct the default limit rate List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Amos Kong Cc: amit.shah@redhat.com, "libvir-list@redhat.com" , qemu-devel@nongnu.org, anthony@codemonkey.ws This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --pbMJXDpHICemVFNUH5IoV1KgPJQAg4KF4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable [adding libvirt] On 11/26/2013 06:58 AM, Paolo Bonzini wrote: > Il 26/11/2013 14:43, Amos Kong ha scritto: >> /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s.= If >> * you have an entropy source capable of generating more entropy than = this >> * and you can pass it through via virtio-rng, then hats off to you. = Until >> * then, this is unlimited for all practical purposes. >> */ >> >> But the current rate is (INT64_MAX) bytes per (1 << 16) ms, it's 128,0= 00 TB/s >=20 > You are changing: >=20 > * max-bytes from 2^63 to 2^47 >=20 > * period from 65536 to 60000 >=20 > For a user, changing only period would have no effect, the limit rate > would remain effectively infinite. Changing max-bytes would give a 7% > higher rate after your patch. >=20 > Not a big deal, and max-bytes is easier to explain after your patch > (bytes/minute) than before (bytes/65536ms). >=20 > Reviewed-by: Paolo Bonzini >=20 Hmm. Libvirt is already converting a user's rate of bytes/period into the qemu parameters, defaulting to 1 second as its default period. Am I correct that as long as libvirt specified both rate AND period, then this change has no impact (and that the 7% change occurs if you specify period while leaving max-bytes alone)? Or is this an ABI change where libvirt will have to be taught to be smart enough to know whether it is old qemu or new qemu to adjust how libvirt does its calculations when converting the user's rate into qemu terms? --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --pbMJXDpHICemVFNUH5IoV1KgPJQAg4KF4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJSlLEFAAoJEKeha0olJ0Nq2OMIAI0NhI/msxa/HSPzQMFTxc2h eakZGzAnuTcYJNoAWERZj1ZN5vUX8YYu0q10ue4Gbux0E644Ao2uz2OPy0sC0mLM /UoiGUf+K8Z4mBn2w3MQg3vl1sSPQs700Wwi1FtrI8XmeXhJhcIEAiV6pXM/qNnN mkYY5lf3XEcDbFzhGvxG+zm2INQalLqygSg0sqwT7TuggvuFEYjvrLSsvjlDP24k 1Vp9Ls+4GoKNScDIkOO6cZ8i4LSR4Nsu/i+VniTpNU3uN4D1q3zta2HD8+fc/VeS j0qht0J1BGVdNNxJ1Q1oJw+jUvhZpx8+br/7OLO40ExkjjSd9lqCdjl8sefcST4= =Ddb4 -----END PGP SIGNATURE----- --pbMJXDpHICemVFNUH5IoV1KgPJQAg4KF4--