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

[Jason Wang <jasowang@redhat.com>]

On Mon, Nov 8, 2021 at 10:50 AM Zhang, Chen <chen.zhang@intel.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Monday, November 8, 2021 10:42 AM
> > 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 4:43 PM Zhang, Chen <chen.zhang@intel.com> wrote:
> > >
> > >
> > >
> > > > -----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.
> >
> > Question still, so we have
> >
> > 1) enable vnet_hdr_support by default
> > 2) add auto_vnet_hdr and enable it by default
> >
> > Using 1) seems much more simpler and can solve this issue. If we depends
> > on the default behaviour, it should be almost the same. If we want to teach
> > the mgmt, both should work. Any other advantages of 2)?
>
> Using 1) we can't ensure user configure parts of module by itself. (vnet_hdr_support = off).
> In this case, filter data already wrong and the filters can't report any transfer error here.

So I think the point is we can't ensure the user configure parts of
module in any case even if auto_vnet_hdr is introduced. E.g user can
choose to disable it manually. That's why I think it should not differ
too much from making vnet_hdr_support enabled by default.

Thanks

>
> Using 2) filters will find/report this issue and try to fix it from local vnet_hdr_len.
>
> Thanks
> Chen
>
> >
> > Thanks
> >
> > >
> > > Thanks
> > > Chen
> > >
> > > >
> > > > I think I may miss something.
> > > >
> > > > Thanks
> > > >
> > > > >
> > > > > Thanks
> > > > > Chen
> > > > >
> > > > > >
> > > > > > Thanks
> > > > > >
> > > > > > >
> > > > > > > Thanks
> > > > > > > Chen
> > > > > > >
> > > > > > > >
> > > > > > > > Thanks
> > > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > > Thanks
> > > > > > > > > Chen
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >>> Thanks
> > > > > > > > >>>
> > > > > > > > >>>> Thanks
> > > > > > > > >>>> Chen
> > > > > > > > >>>>
> > > > > > > > >>>>> Thanks
> > > > > > > > >>>>>
> > > > > > > > >>>>>
> > > > > > >
> > > > >
> > >
>