From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net-next 2/2] net: exit busy loop when another process is runnable Date: Wed, 3 Sep 2014 12:59:39 +0300 Message-ID: <20140903095939.GA8929@redhat.com> References: <53F6F14B.1030609@redhat.com> <20140822074224.GB7372@gmail.com> <53FFEEC0.4000304@redhat.com> <540414AB.9000004@linux.intel.com> <54053998.4040604@redhat.com> <54056076.2030603@linux.intel.com> <20140902083124.GB10356@redhat.com> <5406B9E6.6050103@linux.intel.com> <5406C443.5030109@redhat.com> <20140903093605.GD4783@worktop.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jason Wang , Eliezer Tamir , Ingo Molnar , Mike Galbraith , davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ingo Molnar To: Peter Zijlstra Return-path: Content-Disposition: inline In-Reply-To: <20140903093605.GD4783@worktop.ger.corp.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Sep 03, 2014 at 11:36:05AM +0200, Peter Zijlstra wrote: > On Wed, Sep 03, 2014 at 03:33:23PM +0800, Jason Wang wrote: > > A new issue is for virt users. I implement busy polling for virtio-net > > but we don't want one vcpu monopoly the cpu if there's some tasks on > > other vcpus. We may need some hint from host to guest to let it exit the > > loop if needed. > > Aw god.. virt nonsense is wrecking things again. I don't see a reason to bring virt up here. Original patch shows improvement with a simple loopback netperf test. Some people like the linux kernel so much, they want to run many instances of it on the same CPU. Understandable. So of course everything is then magnified x2 as you are running two schedulers and two networking stacks, but let's focus on the important thing which is better interaction between busy polling and the linux scheduler. -- MST