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From: Stanislav Fomichev <sdf@fomichev.me>
To: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Toshiaki Makita <toshiaki.makita1@gmail.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	Yonghong Song <yhs@fb.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	Jiri Pirko <jiri@resnulli.us>,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	William Tu <u9012063@gmail.com>
Subject: Re: [RFC PATCH bpf-next 00/14] xdp_flow: Flow offload to XDP
Date: Fri, 16 Aug 2019 09:20:29 -0700
Message-ID: <20190816162029.GR2820@mini-arch> (raw)
In-Reply-To: <20190816155911.GP2820@mini-arch>

On 08/16, Stanislav Fomichev wrote:
> On 08/15, Jakub Kicinski wrote:
> > On Thu, 15 Aug 2019 08:21:00 -0700, Stanislav Fomichev wrote:
> > > On 08/15, Toshiaki Makita wrote:
> > > > On 2019/08/15 2:07, Stanislav Fomichev wrote:  
> > > > > On 08/13, Toshiaki Makita wrote:  
> > > > > > * Implementation
> > > > > > 
> > > > > > xdp_flow makes use of UMH to load an eBPF program for XDP, similar to
> > > > > > bpfilter. The difference is that xdp_flow does not generate the eBPF
> > > > > > program dynamically but a prebuilt program is embedded in UMH. This is
> > > > > > mainly because flow insertion is considerably frequent. If we generate
> > > > > > and load an eBPF program on each insertion of a flow, the latency of the
> > > > > > first packet of ping in above test will incease, which I want to avoid.  
> > > > > Can this be instead implemented with a new hook that will be called
> > > > > for TC events? This hook can write to perf event buffer and control
> > > > > plane will insert/remove/modify flow tables in the BPF maps (contol
> > > > > plane will also install xdp program).
> > > > > 
> > > > > Why do we need UMH? What am I missing?  
> > > > 
> > > > So you suggest doing everything in xdp_flow kmod?  
> > > You probably don't even need xdp_flow kmod. Add new tc "offload" mode
> > > (bypass) that dumps every command via netlink (or calls the BPF hook
> > > where you can dump it into perf event buffer) and then read that info
> > > from userspace and install xdp programs and modify flow tables.
> > > I don't think you need any kernel changes besides that stream
> > > of data from the kernel about qdisc/tc flow creation/removal/etc.
> > 
> > There's a certain allure in bringing the in-kernel BPF translation
> > infrastructure forward. OTOH from system architecture perspective IMHO
> > it does seem like a task best handed in user space. bpfilter can replace
> > iptables completely, here we're looking at an acceleration relatively
> > loosely coupled with flower.
> Even for bpfilter I would've solved it using something similar:
> iptables bypass + redirect iptables netlink requests to some
> userspace helper that was registered to be iptables compatibility
> manager. And then, again, it becomes a purely userspace problem.
Oh, wait, isn't iptables kernel api is setsockopt/getsockopt?
With the new cgroup hooks you can now try to do bpfilter completely
in BPF 🤯

> The issue with UMH is that the helper has to be statically compiled
> from the kernel tree, which means we can't bring in any dependencies
> (stuff like libkefir you mentioned below).
> 
> But I digress :-)
> 
> > FWIW Quentin spent some time working on a universal flow rule to BPF
> > translation library:
> > 
> > https://github.com/Netronome/libkefir
> > 
> > A lot remains to be done there, but flower front end is one of the
> > targets. A library can be tuned for any application, without a
> > dependency on flower uAPI.
> > 
> > > But, I haven't looked at the series deeply, so I might be missing
> > > something :-)
> > 
> > I don't think you are :)

  reply index

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13 12:05 Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 01/14] xdp_flow: Add skeleton of XDP based TC offload driver Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 02/14] xdp_flow: Add skeleton bpf program for XDP Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 03/14] bpf: Add API to get program from id Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 04/14] xdp_flow: Attach bpf prog to XDP in kernel after UMH loaded program Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 05/14] xdp_flow: Prepare flow tables in bpf Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 06/14] xdp_flow: Add flow entry insertion/deletion logic in UMH Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 07/14] xdp_flow: Add flow handling and basic actions in bpf prog Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 08/14] xdp_flow: Implement flow replacement/deletion logic in xdp_flow kmod Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 09/14] xdp_flow: Add netdev feature for enabling TC flower offload to XDP Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 10/14] xdp_flow: Implement redirect action Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 11/14] xdp_flow: Implement vlan_push action Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 12/14] bpf, selftest: Add test for xdp_flow Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 13/14] i40e: prefetch xdp->data before running XDP prog Toshiaki Makita
2019-08-13 12:05 ` [RFC PATCH bpf-next 14/14] bpf, hashtab: Compare keys in long Toshiaki Makita
2019-08-14  1:44 ` [RFC PATCH bpf-next 00/14] xdp_flow: Flow offload to XDP Alexei Starovoitov
2019-08-14  7:33   ` Toshiaki Makita
2019-08-15 10:59     ` Toshiaki Makita
2019-08-14 17:07 ` Stanislav Fomichev
2019-08-15 10:26   ` Toshiaki Makita
2019-08-15 15:21     ` Stanislav Fomichev
2019-08-15 19:22       ` Jakub Kicinski
2019-08-16  1:28         ` Toshiaki Makita
2019-08-16 18:52           ` Jakub Kicinski
2019-08-17 14:01             ` Toshiaki Makita
2019-08-19 18:15               ` Jakub Kicinski
2019-08-21  8:49                 ` Toshiaki Makita
2019-08-21 18:38                   ` Jakub Kicinski
2019-08-16 15:59         ` Stanislav Fomichev
2019-08-16 16:20           ` Stanislav Fomichev [this message]
2019-08-16  1:09       ` Toshiaki Makita
2019-08-16 15:35         ` Stanislav Fomichev
2019-08-17 14:10           ` Toshiaki Makita
2019-08-15 15:46 ` William Tu
2019-08-16  1:38   ` Toshiaki Makita

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