From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zhi Yong Wu Subject: Fwd: [RFC PATCH net-next 0/3] virtio_net: add aRFS support Date: Thu, 16 Jan 2014 16:34:10 +0800 Message-ID: References: <1389795654-28381-1-git-send-email-zwu.kernel@gmail.com> <52D75EA5.1050000@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Linux Netdev List , Tom Herbert , Eric Dumazet , "David S. Miller" , Zhi Yong Wu , "Michael S. Tsirkin" , Rusty Russell , Jason Wang To: Stefan Hajnoczi Return-path: Received: from mail-ob0-f177.google.com ([209.85.214.177]:61649 "EHLO mail-ob0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751024AbaAPIeL (ORCPT ); Thu, 16 Jan 2014 03:34:11 -0500 Received: by mail-ob0-f177.google.com with SMTP id wp18so390675obc.8 for ; Thu, 16 Jan 2014 00:34:10 -0800 (PST) In-Reply-To: <52D75EA5.1050000@redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: CC: stefanha, MST, Rusty Russel ---------- Forwarded message ---------- From: Jason Wang Date: Thu, Jan 16, 2014 at 12:23 PM Subject: Re: [RFC PATCH net-next 0/3] virtio_net: add aRFS support To: Zhi Yong Wu Cc: netdev@vger.kernel.org, therbert@google.com, edumazet@google.com, davem@davemloft.net, Zhi Yong Wu On 01/15/2014 10:20 PM, Zhi Yong Wu wrote: > > From: Zhi Yong Wu > > HI, folks > > The patchset is trying to integrate aRFS support to virtio_net. In this case, > aRFS will be used to select the RX queue. To make sure that it's going ahead > in the correct direction, although it is still one RFC and isn't tested, it's > post out ASAP. Any comment are appreciated, thanks. > > If anyone is interested in playing with it, you can get this patchset from my > dev git on github: > git://github.com/wuzhy/kernel.git virtnet_rfs > > Zhi Yong Wu (3): > virtio_pci: Introduce one new config api vp_get_vq_irq() > virtio_net: Introduce one dummy function virtnet_filter_rfs() > virtio-net: Add accelerated RFS support > > drivers/net/virtio_net.c | 67 ++++++++++++++++++++++++++++++++++++++++- > drivers/virtio/virtio_pci.c | 11 +++++++ > include/linux/virtio_config.h | 12 +++++++ > 3 files changed, 89 insertions(+), 1 deletions(-) > Please run get_maintainter.pl before sending the patch. You'd better at least cc virtio maintainer/list for this. The core aRFS method is a noop in this RFC which make this series no much sense to discuss. You should at least mention the big picture here in the cover letter. I suggest you should post a RFC which can run and has expected result or you can just raise a thread for the design discussion. And this method has been discussed before, you can search "[net-next RFC PATCH 5/5] virtio-net: flow director support" in netdev archive for a very old prototype implemented by me. It can work and looks like most of this RFC have already done there. A basic question is whether or not we need this, not all the mq cards use aRFS (see ixgbe ATR). And whether or not it can bring extra overheads? For virtio, we want to reduce the vmexits as much as possible but this aRFS seems introduce a lot of more of this. Making a complex interfaces just for an virtual device may not be good, simple method may works for most of the cases. We really should consider to offload this to real nic. VMDq and L2 forwarding offload may help in this case. -- Regards, Zhi Yong Wu