From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: Bug in KVM clock backwards compensation Date: Fri, 29 Apr 2011 00:38:01 +0200 Message-ID: <4DB9EC49.3050006@web.de> References: <4DB9106D.6040203@redhat.com> <4DB911D9.3010409@web.de> <20110428072209.GH20365@amd.com> <4DB9BACD.2090609@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigF16FB786673BFDC7FDCCA8EC" Cc: "Roedel, Joerg" , kvm To: Zachary Amsden Return-path: Received: from fmmailgate02.web.de ([217.72.192.227]:35893 "EHLO fmmailgate02.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932595Ab1D1WiO (ORCPT ); Thu, 28 Apr 2011 18:38:14 -0400 In-Reply-To: <4DB9BACD.2090609@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigF16FB786673BFDC7FDCCA8EC Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 2011-04-28 21:06, Zachary Amsden wrote: > On 04/28/2011 12:22 AM, Roedel, Joerg wrote: >> On Thu, Apr 28, 2011 at 03:06:01AM -0400, Jan Kiszka wrote: >> =20 >>> And /me still wonders (like I did when this first popped up) if the >>> proper place of determining TSC stability really have to be KVM. >>> >>> If the Linux core fails to detect some instability and KVM has to jum= p >>> in, shouldn't we better improve the core's detection abilities and ma= ke >>> use of them in KVM? Conceptually this looks like we are currently jus= t >>> working around a core deficit in KVM. >>> =20 >> Yes, good question. Has this ever triggered on a real machine (not >> counting the suspend/resume issue in)? >> =20 >=20 > Yes... some platforms don't go haywire until you start using power > mangement, TSC is stable before that, but not afterwards, and depending= > on the version of the kernel, KVM might detect this before the kernel d= oes. >=20 > Honestly, the code is obsolete, but still useful for those who build KV= M > as an external module on older kernels using the kvm-kmod system. I'll happily accept patches that migrate any logic to kvm-kmod that the current kernel does not need it anymore. Jan --------------enigF16FB786673BFDC7FDCCA8EC Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.15 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org/ iEYEARECAAYFAk257E4ACgkQitSsb3rl5xTb7ACfampd1Y3dmEIZ7zSdX7zCIJwg Lt0AoKRduLZrEYL/JjpkaIhDTE39nkx0 =N/2U -----END PGP SIGNATURE----- --------------enigF16FB786673BFDC7FDCCA8EC--