Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751463AbbHASsi (ORCPT ); Sat, 1 Aug 2015 14:48:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52941 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751292AbbHASsf (ORCPT ); Sat, 1 Aug 2015 14:48:35 -0400 From: Bandan Das To: Eyal Moscovici Cc: "Michael S. Tsirkin" , cgroups@vger.kernel.org, jasowang@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Razya Ladelsky Subject: Re: [RFC PATCH 0/4] Shared vhost design References: <1436760455-5686-1-git-send-email-bsd@redhat.com> <20150728000221-mutt-send-email-mst@redhat.com> Date: Sat, 01 Aug 2015 14:48:33 -0400 In-Reply-To: (Eyal Moscovici's message of "Sat, 1 Aug 2015 12:14:10 +0300") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2037 Lines: 50 Eyal Moscovici writes: ... > > We can start to implement polling, but I am unsure if the cgroups > integration > will be sufficient. The polling vhost thread should be scheduled all > the time and just moving it from one cgroup to the other wont be > sufficient. > I think it needs a deeper integration to the point where either we have a > vhost thread for each cgroup or the vhost thread enforces the cgroup > policies over its polled VM guests. Agreed, what we have with cgroups is not sufficient. I am waiting for Tejun et al to comment on our approach :) Michael mentioned whether it's possible to integrate cgroups into workgroups which I think is a more generic and the preferred solution. I just don't know yet how easy/difficult it is to implement this with the new cgroups unified hierarchy. BTW, I am working on the numbers you had asked for. Honestly, I think the cost of cgroups could be similar to running a vhost thread/guest since that is how cgroups integration currently works. But it's good to have the numbers before us. >> >> So simple polling by vhost is kind of ok for some guests, but I think to >> really make it work for a reasonably wide selection of guests/workloads >> you need to combine it with 1. polling the NIC - it makes no sense to me >> to only poll one side of the equation; and probably 2. - polling in >> guest. >> > > I agree that we need polling on the NIC which could probably be achieved > by using > the polling interface introduced in kernel 3.11: > http://lwn.net/Articles/551284/ > although I never tried using it myself. > About your point about polling inside the guest, I think it is orthogonal > to polling > in the host. > > > Eyal Moscovici > HL-Cloud Infrastructure Solutions > IBM Haifa Research Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/