From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f178.google.com (mail-wi0-f178.google.com [209.85.212.178]) by dpdk.org (Postfix) with ESMTP id 3ECB9959 for ; Fri, 12 Dec 2014 00:18:37 +0100 (CET) Received: by mail-wi0-f178.google.com with SMTP id em10so910787wid.5 for ; Thu, 11 Dec 2014 15:18:37 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=0J/Mw1eL3xTe7ZJNI9qnC1M1sUGweZXtI0NZS7FwxTQ=; b=KRYblgLI/Su7QMdjwJnhbVr1eY7D1XHZOx6CSvMU8LZb9OQzFFYJXZjp5JgSNdIU7e drYcxFwBO1LtATConi2WiISLsQoSwo534GqqR5r1pFKaDk40qxrHhdjoOa8jfkduKhSr gY122u7emynMCr7hdKztDw/lSIeS1O430KsNQmBgqRn6Hi+jtF6euxi3TNyixhWb5Kx9 jKQx/h1yzSk1BANUTLH9WjJsWDfEBv6cfVY/sfMilqxR8PXkVPHSP/hisCKvQ1x0JYSa ORE5uepHpnbwIP4M6Z22RdKd3u9EePYP3wli7Tm1zARXQv4xbXj1YPZ+zhDEt36fzhzl OoEg== X-Gm-Message-State: ALoCoQkoAcV2zq04RuyrB7Yr22C/1nt1KZPodP9kgSm54p8qrBZ7NkadSp5M8p3we4k6g0p5llhb X-Received: by 10.180.90.133 with SMTP id bw5mr2366774wib.50.1418339917112; Thu, 11 Dec 2014 15:18:37 -0800 (PST) Received: from xps13.localnet ([88.249.222.12]) by mx.google.com with ESMTPSA id ry19sm3460837wjb.3.2014.12.11.15.18.35 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 11 Dec 2014 15:18:36 -0800 (PST) From: Thomas Monjalon To: Alan Carew , Pablo de Lara Date: Fri, 12 Dec 2014 00:18:08 +0100 Message-ID: <10291528.MoKaz8pbFD@xps13> Organization: 6WIND User-Agent: KMail/4.14.3 (Linux/3.17.4-1-ARCH; KDE/4.14.3; x86_64; ; ) 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" Cc: dev@dpdk.org, Paolo Bonzini , qemu-devel Subject: Re: [dpdk-dev] [PATCH v4 00/10] VM Power Management X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Dec 2014 23:18:37 -0000 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