From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Samudrala, Sridhar" Subject: Re: [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available Date: Tue, 19 Dec 2017 14:37:50 -0800 Message-ID: References: <20171219174259-mutt-send-email-mst@kernel.org> <20171219095548.61d70d10@xeon-e3> <20171219.132117.666798483874609477.davem@davemloft.net> <20171219104159.30d9caaf@xeon-e3> <344f0afc-b4aa-9f1a-15b8-166ba97d270b@intel.com> <20171219114627.76dac732@xeon-e3> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: David Miller , mst@redhat.com, netdev@vger.kernel.org, virtualization@lists.linux-foundation.org, alexander.duyck@gmail.com, jesse.brandeburg@intel.com To: Stephen Hemminger Return-path: Received: from mga11.intel.com ([192.55.52.93]:39898 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751820AbdLSWhv (ORCPT ); Tue, 19 Dec 2017 17:37:51 -0500 In-Reply-To: <20171219114627.76dac732@xeon-e3> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 12/19/2017 11:46 AM, Stephen Hemminger wrote: > On Tue, 19 Dec 2017 11:42:33 -0800 > "Samudrala, Sridhar" wrote: > >> On 12/19/2017 10:41 AM, Stephen Hemminger wrote: >>> On Tue, 19 Dec 2017 13:21:17 -0500 (EST) >>> David Miller wrote: >>> >>>> From: Stephen Hemminger >>>> Date: Tue, 19 Dec 2017 09:55:48 -0800 >>>> >>>>> could be 10ms, just enough to let udev do its renaming >>>> Please, move to some kind of notification or event based handling of >>>> this problem. >>>> >>>> No delay is safe, what if userspace gets swapped out or whatever >>>> else might make userspace stall unexpectedly? >>>> >>> The plan is to remove the delay and do the naming in the kernel. >>> This was suggested by Lennart since udev is only doing naming policy >>> because kernel names were not repeatable. >>> >>> This makes the VF show up as "ethN_vf" on Hyper-V which is user friendly. >>> >>> Patch is pending. >> Do we really need to delay the setup until the name is changed? >> Can't we call dev_set_mtu() and dev_open() until dev_change_name() is done? >> >> Thanks >> Sridhar > You can call dev_set_mtu, but when dev_open is done the device name > can not be changed by userspace. I did a quick test to remove the delay and also the dev_open() call and i don't see any issues with virtio taking over the VF datapath. Only the netdev_info() messages may show old device name. Any specific scenario where we need to explicitly call  VF's dev_open() in the VF setup process? I tried i40evf driver loaded after virtio_net  AND  virtio_net loading after i40evf. Thanks Sridhar