From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52565) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XzD0O-0003DT-Ug for qemu-devel@nongnu.org; Thu, 11 Dec 2014 18:18:51 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XzD0I-0003Pc-ML for qemu-devel@nongnu.org; Thu, 11 Dec 2014 18:18:44 -0500 Received: from mail-wi0-f180.google.com ([209.85.212.180]:54223) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XzD0I-0003PK-GG for qemu-devel@nongnu.org; Thu, 11 Dec 2014 18:18:38 -0500 Received: by mail-wi0-f180.google.com with SMTP id n3so880630wiv.13 for ; Thu, 11 Dec 2014 15:18:37 -0800 (PST) From: Thomas Monjalon Date: Fri, 12 Dec 2014 00:18:08 +0100 Message-ID: <10291528.MoKaz8pbFD@xps13> In-Reply-To: <548732C9.2020201@redhat.com> References: <1412003903-9061-1-git-send-email-alan.carew@intel.com> <5470C514.3080307@6wind.com> <548732C9.2020201@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Subject: Re: [Qemu-devel] [dpdk-dev] [PATCH v4 00/10] VM Power Management List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alan Carew , Pablo de Lara Cc: dev@dpdk.org, Paolo Bonzini , qemu-devel 2014-12-09 18:35, Paolo Bonzini: > >>>> Did you make any progress in Qemu/KVM community? > >>>> We need to be sync'ed up with them to be sure we share the same goal. > >>>> I want also to avoid using a solution which doesn't fit with their > >>>> plan. > >>>> Remember that we already had this problem with ivshmem which was > >>>> planned to be dropped. > >>> > >>> Unfortunately, I have not yet received any feedback: > >>> http://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg01103.html > >> > >> Just to add to what Alan said above, this capability does not exist in > >> qemu at the moment, and based on there having been no feedback on th > >> qemu mailing list so far, I think it's reasonable to assume that it > >> will not be implemented in the immediate future. The VM Power > >> Management feature has also been designed to allow easy migration to a > >> qemu-based solution when this is supported in future. Therefore, I'd > >> be in favour of accepting this feature into DPDK now. > >> > >> It's true that the implementation is a work-around, but there have > >> been similar cases in DPDK in the past. One recent example that comes > >> to mind is userspace vhost. The original implementation could also be > >> considered a work-around, but it met the needs of many in the > >> community. Now, with support for vhost-user in qemu 2.1, that > >> implementation is being improved. I'd see VM Power Management > >> following a similar path when this capability is supported in qemu. > > I wonder if this might be papering over a bug in the host cpufreq > driver. If the guest is not doing much and leaving a lot of idle CPU > time, the host should scale down the frequency of that CPU. In the case > of pinned VCPUs this should really "just work". What is the problem > that is being solved? > > Paolo Alan, Pablo, please could you explain your logic with VM power management? -- Thomas