From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55245) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d7z89-0000uk-EB for qemu-devel@nongnu.org; Tue, 09 May 2017 03:00:22 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1d7z86-0005bp-EK for qemu-devel@nongnu.org; Tue, 09 May 2017 03:00:21 -0400 Received: from [59.151.112.132] (port=65234 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1d7z85-0005a5-FR for qemu-devel@nongnu.org; Tue, 09 May 2017 03:00:18 -0400 References: <1493372840-24551-1-git-send-email-zhangchen.fnst@cn.fujitsu.com> <1493372840-24551-6-git-send-email-zhangchen.fnst@cn.fujitsu.com> <7bde3681-280c-764a-71df-f4a1cc4b7011@redhat.com> <4cc14276-55bc-2981-cbdd-4d66ae6be59e@cn.fujitsu.com> <09077119-d9bb-c367-799a-a0718664cdc7@cn.fujitsu.com> <97099db3-169d-178c-01ab-73194167677a@redhat.com> From: Zhang Chen Message-ID: <9fd0649c-caa0-9c4c-adf0-276a0ec6801f@cn.fujitsu.com> Date: Tue, 9 May 2017 14:59:55 +0800 MIME-Version: 1.0 In-Reply-To: <97099db3-169d-178c-01ab-73194167677a@redhat.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH V3 05/10] net/net.c: Add vnet header length to SocketReadState List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Wang , qemu devel Cc: zhangchen.fnst@cn.fujitsu.com, zhanghailiang , Li Zhijian , weifuqiang , "eddie . dong" , bian naimeng On 05/09/2017 01:36 PM, Jason Wang wrote: > > > On 2017年05月09日 12:03, Zhang Chen wrote: >> >> >> On 05/09/2017 10:40 AM, Jason Wang wrote: >>> >>> >>> On 2017年05月08日 11:47, Zhang Chen wrote: >>>> >>>> >>>> On 05/03/2017 06:42 PM, Jason Wang wrote: >>>>> >>>>> >>>>> On 2017年05月03日 11:43, Zhang Chen wrote: >>>>>> >>>>>> >>>>>> On 05/02/2017 12:53 PM, Jason Wang wrote: >>>>>>> >>>>>>> >>>>>>> On 2017年04月28日 17:47, Zhang Chen wrote: >>>>>>>> Address Jason Wang's comments add vnet header length to >>>>>>>> SocketReadState. >>>>>>> >>>>>>> Instead of saying this, you can add "Suggested-by: Jason Wang >>>>>>> " above your sign-off. >>>>>> >>>>>> OK. >>>>>> >>>>>>> >>>>>>>> So we change net_fill_rstate() to read >>>>>>>> struct {int size; int vnet_hdr_len; const uint8_t buf[];}. >>>>>>> >>>>>>> This makes me thinking about the backward compatibility. I think >>>>>>> we'd better try to keep it as much as possible. E.g how about >>>>>>> pack vnet_hdr_len into higher bits of size? >>>>>>> >>>>>> >>>>>> Do you means split uint32_t size to uint16_t size and uint16_t >>>>>> vnet_hdr_len ? >>>>>> If yes, we also can't keep compatibility with old version. >>>>>> Old code send a uint32_t size, we read it as uint16_t size is >>>>>> always wrong. >>>>>> >>>>>> Thanks >>>>>> Zhang Chen >>>>> >>>>> Consider it's unlikely to send or receive packet >= 64K, we can >>>>> reuse higher bits (e.g highest 8 bits). Then we can still read >>>>> uint32_t and then check its highest 8 bits. If it was zero, we >>>>> know vnet header is zero, if not it could be read as vnet header >>>>> length. >>>> >>>> I got your point, but in this way, packet size must < 64K, if size >>>> >=64K we still can't maintain the backward compatibility, >>>> For the packet sender that didn't know the potential packet size >>>> limit, I think we should make code explicitly declared like >>>> currently code. Otherwise we will make other people confused and >>>> make code difficult to maintain. >>>> >>>> Thanks >>>> Zhang Chen >>>> >>> >>> Yes, this is an possible issue in the future. Rethink about this, >>> what if we just compare vnet header? Is there any issue of doing >>> this? (Sorry, I remember this is a reason, but forget now). >> >> Yes, we can compare all packet with vnet header, the compare >> performance is very low. but we can't parse raw packet to >> tcp/udp/icmp packet, because we didn't know the vnet_hdr_len as the >> offset. >> >> Thanks >> Zhang Chen > > Aha, so I think it's time to use the new format but: > > - probably need a new option to enable this support for filter Do you means we should add the new option for every filter object like that: Now: -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0 Feature: -object filter-mirror,id=m0,netdev=hn0,queue=tx,outdev=mirror0,has_vnet_hdr_len=on And colo-compare also need this option to get the vnet_hdr_len. > - let's don't touch socket backend, and make it still can work with > filters whose vnet_hder is off OK, Maybe we can add a new variable in net_fill_rstate(). Thanks Zhang Chen > > Thanks > >> >>> >>> Thanks >>> >>> >>> . >>> >> > > > > . > -- Thanks Zhang Chen