From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric B Munson Subject: Re: [PATCH 0/5 V5] Avoid soft lockup message when KVM is stopped by host Date: Thu, 15 Dec 2011 13:53:46 -0500 Message-ID: <20111215185346.GA2829@mgebm.net> References: <1323116344-17911-1-git-send-email-emunson@mgebm.net> <4EDF7B0D.4060001@redhat.com> <20111208151929.GA6301@mgebm.net> <4EE8BBF4.8070108@redhat.com> <20111214175844.GD4075@mgebm.net> <4EE9C274.3030603@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="Dxnq1zWXvFF0Q93v" Return-path: Received: from oz.csail.mit.edu ([128.30.30.239]:45597 "EHLO mail.mgebm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759239Ab1LOSxs (ORCPT ); Thu, 15 Dec 2011 13:53:48 -0500 Content-Disposition: inline In-Reply-To: <4EE9C274.3030603@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Avi Kivity Cc: mingo@redhat.com, hpa@zytor.com, arnd@arndb.de, ryanh@linux.vnet.ibm.com, aliguori@us.ibm.com, mtosatti@redhat.com, jeremy.fitzhardinge@citrix.com, levinsasha928@gmail.com, Jan Kiszka , kvm@vger.kernel.org, linux-arch@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org --Dxnq1zWXvFF0Q93v Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, 15 Dec 2011, Avi Kivity wrote: > On 12/14/2011 07:58 PM, Eric B Munson wrote: > > > I don't think you should see a guest softlockup if the host is > > > overloaded. Nor should you see it due to a long live migration pause, > > > or STOP/CONT. You should see a guest softlockup if it is spinning due > > > to a guest bug, and not for any other reason. > > >=20 > > > I think we need a mix of the ioctl (for STOP/CONT and voluntary pause= s, > > > like live migration or qemu stop/cont) and preempt notifiers (together > > > with a check for TASK_RUNNING/TASK_UNINTERRUPTIBLE, for scheduling or > > > swap delays) > > >=20 > > > > Do you want the preemption notifier work in before you will consider me= rging > > this set, or can that be a follow on? >=20 > Yes please. >=20 > --=20 > error compiling committee.c: too many arguments to function >=20 I am working on V7 to incorporate the __this_cpu_and suggestion, would you consider that for inclusion and we can continue discussing the need for the preemption notification work? I think that having a guest complain when the host is so loaded that the guest watchdog threads can't make any progress is desirable behavior, it may be the only notification that an admin gets that= a particular host is over loaded. Eric --Dxnq1zWXvFF0Q93v Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iQIcBAEBAgAGBQJO6kI6AAoJEKhG9nGc1bpJIbUP/3G9PFXfFMlQ1URaJG5PAGHT 0UNQ1DYgJhHhh4nZ8Xvvbu3KFpgtTI7ZLt+tFHyVy4dUv13P4M7w995zUgVPMwzO IxTRtTpCNDou2bQv6iZSQpBqQ2EPniWt0ST3Rm+OztAwedX5govi0uYHJKhh5fJA 9E8FmfhpyYYrM/UPDL9l1OtMMfIrdNBT1u7IjCKfSB/8hmOoCFtJocHVdqDhGia4 RGPgjEy+KfPBaqE6MkUWEgyWrVw72vmP7aMRE6sLEywjjR4jbD5LVeNl9q6b6whY Oinqb6GavyttXHn2aVIxZw5DfGPsfzrh8VLDc9fV8SItKnqNm6quvWO5eLgUPxPL 5b6KsjMMm8m9c4UK6qZHOVS7AXxUx5HSzGIQJlqUS/piLBFuzFQNi91EHRic+4cq nXKojyqUOqg67gimibBJMGSijs+BdB9RuNciqi65eMp6Yspk51p1WtPCZzXaH1hY cuSUGXf5E+GNHOrAxLfRGErs3t4tuYaZl+osqyFfJuYFzP8NMWVdvN5vTirxd6C7 XPVeGzWdDGGtUD5jt0A2ZaNuiu8ZUAj23GWGkEebL1hr2glPQT6eNGOzMdQfHDUl ss7BbxJBUlXgn0GmmDKw2qZyiP68CA1tnjC4/JdJmH/oq4jc/hrhkaPpJyf/Ln+r gmgDTEKoMJNlzwE+GBvF =Ifx8 -----END PGP SIGNATURE----- --Dxnq1zWXvFF0Q93v--