RE: [PATCH V5 1/3] net/filter: Optimize transfer protocol for filter-mirror/redirector

["Zhang, Chen" <chen.zhang@intel.com>]

> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Friday, November 5, 2021 4:30 PM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Markus Armbruster <armbru@redhat.com>; qemu-dev <qemu-
> devel@nongnu.org>; Li Zhijian <lizhijian@cn.fujitsu.com>
> Subject: Re: [PATCH V5 1/3] net/filter: Optimize transfer protocol for filter-
> mirror/redirector
> 
> On Fri, Nov 5, 2021 at 1:29 PM Zhang, Chen <chen.zhang@intel.com> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Jason Wang <jasowang@redhat.com>
> > > Sent: Friday, November 5, 2021 12:03 PM
> > > To: Zhang, Chen <chen.zhang@intel.com>
> > > Cc: Markus Armbruster <armbru@redhat.com>; qemu-dev <qemu-
> > > devel@nongnu.org>; Li Zhijian <lizhijian@cn.fujitsu.com>
> > > Subject: Re: [PATCH V5 1/3] net/filter: Optimize transfer protocol
> > > for filter- mirror/redirector
> > >
> > > On Fri, Nov 5, 2021 at 11:27 AM Zhang, Chen <chen.zhang@intel.com>
> wrote:
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Jason Wang <jasowang@redhat.com>
> > > > > Sent: Friday, November 5, 2021 11:17 AM
> > > > > To: Zhang, Chen <chen.zhang@intel.com>; Markus Armbruster
> > > > > <armbru@redhat.com>
> > > > > Cc: qemu-dev <qemu-devel@nongnu.org>; Li Zhijian
> > > > > <lizhijian@cn.fujitsu.com>
> > > > > Subject: Re: [PATCH V5 1/3] net/filter: Optimize transfer
> > > > > protocol for filter- mirror/redirector
> > > > >
> > > > >
> > > > > 在 2021/11/4 下午1:37, Zhang, Chen 写道:
> > > > > >>>>>
> > > > > >>>>> I wonder if we need to introduce new parameter, e.g
> > > > > >>>>> force_vnet_hdr here, then we can always send vnet_hdr
> when
> > > > > >>>>> it
> > > is enabled.
> > > > > >>>>>
> > > > > >>>>> Otherwise the "vnet_hdr_support" seems meaningless.
> > > > > >>>> Yes, Current "vnet_hdr_support"  default enabled, and
> > > > > >>>> vnet_hdr_len
> > > > > >>> already forced from attached nf->netdev.
> > > > > >>>> Maybe we can introduce a new parameter
> "force_no_vnet_hdr"
> > > here
> > > > > to
> > > > > >>> make the vnet_hdr_len always keep 0.
> > > > > >>>> If you think OK, I will update it in next version.
> > > > > >>> Let me explain, if I was not wrong:
> > > > > >>>
> > > > > >>> "vnet_hdr_support" means whether or not to send vnet header
> > > length.
> > > > > >>> If vnet_hdr_support=false, we won't send the vnet header.
> > > > > >>> This looks the same as you "force_no_vent_hdr" above.
> > > > > >> Yes, It was.  But this series changed it.
> > > > > >> Current "vnet_hdr_support" can't decide whether send vnet
> > > > > >> header length, we always send it even 0.
> > > > > >> It will avoid sender/receiver transfer protocol parse issues:
> > > > > >> When sender data with the vnet header length, but receiver
> > > > > >> can't enable the "vnet_hdr_support".
> > > > > >> Filters will auto setup vnet_hdr_len as local nf->netdev and
> > > > > >> found the issue when get different vnet_hdr_len from other
> filters.
> > > > > >>
> > > > > >>> And my "force_vnet_hdr" seems duplicated with
> > > > > vnet_hdr_support=true.
> > > > > >>> So it looks to me we can leave the mirror code as is and
> > > > > >>> just change the compare? (depends on the mgmt to set a
> > > > > >>> correct
> > > > > >>> vnet_hdr_support)
> > > > > >> OK, I will keep the
> > > > > >> filter-mirror/filter-redirector/filter-rewriter
> > > > > >> same as this version.
> > > > > >> For the colo-compare module, It will get primary node's
> > > > > >> filter data's vnet_hdr_len as the local value, And compare
> > > > > >> with secondary node's, because it is not attached any nf->netdev.
> > > > > >> So, it looks compare module's "vnet_hdr_support" been auto
> > > > > >> configuration from the filter transport protocol.
> > > > > >> If the "force_vnet_hdr" means hard code a compare's local
> > > > > >> vnet_hdr_len rather than come from input filter's data?
> > > > > >>
> > > > > >> Thanks
> > > > > >> Chen
> > > > > >>
> > > > > > Hi Jason/Markus,
> > > > > >
> > > > > > Rethink about it, How about keep the original "vnet_hdr_support"
> > > > > > function, And add a new optional parameter "auto_vnet_hdr" for
> > > > > filters/compare?
> > > > >
> > > > >
> > > > > It's a way but rethink of the whole thing. I wonder what if we
> > > > > just enable "vnet_hdr_support" by default for filter and colo-
> compare?
> > > >
> > > > It's works by default for user use -device virtio-net-pci and e1000...
> > > > But it can't resolve this series motivation, how to fix/check user
> > > configuration issue:
> > > > For example user enable " vnet_hdr_support " filter-mirror and
> > > > disable " vnet_hdr_support" filter-redirector And connect both
> > > > filter modules by
> > > chardev socket.
> > > > In this case guest will get wrong network workload and filters
> > > > didn’t perceive any abnormalities, but in fact, the whole system
> > > > is no longer
> > > working.
> > > > This series will report error and try to correct it.
> > >
> > > The problem is how "auto_vnet_hdr" help in this case. It's a new
> > > parameter which may lead to more wrong configuration?
> >
> > No, the "auto_vnet_hdr" will fix most the wrong configuration issues as
> "vnet_hdr_support" correct setting.
> > When we enable the "auto_vnet_hdr", the original "vnet_hdr_support"
> will no effect.
> 
> So it looks to me it still depends on the management to set "auto_vnet_hdr"
> to be true? (or make it enabled by default)

Yes, I plan to make "auto_vnet_hdr" enabled by default in next version. 

> 
> If we can do that, isn't it much more simpler to make vnet_hdr_support by
> default?

Yes, For compatibility filters and COLO still work with the original "vnet_hdr_support".
For new users, they can enable the new "auto_vnet_hdr" to avoid some issues.

Thanks
Chen

> 
> I think I may miss something.
> 
> Thanks
> 
> >
> > Thanks
> > Chen
> >
> > >
> > > Thanks
> > >
> > > >
> > > > Thanks
> > > > Chen
> > > >
> > > > >
> > > > > Thanks
> > > > >
> > > > >
> > > > > >
> > > > > > Thanks
> > > > > > Chen
> > > > > >
> > > > > >
> > > > > >>> Thanks
> > > > > >>>
> > > > > >>>> Thanks
> > > > > >>>> Chen
> > > > > >>>>
> > > > > >>>>> Thanks
> > > > > >>>>>
> > > > > >>>>>
> > > >
> >