BPF Archive on lore.kernel.org
 help / color / Atom feed
From: Toshiaki Makita <toshiaki.makita1@gmail.com>
To: Stanislav Fomichev <sdf@fomichev.me>
Cc: 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>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	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: Sat, 17 Aug 2019 23:10:10 +0900
Message-ID: <11ab8890-f876-250e-1a52-eab0bf057640@gmail.com> (raw)
In-Reply-To: <20190816153550.GO2820@mini-arch>

On 19/08/17 (土) 0:35:50, Stanislav Fomichev wrote:
> On 08/16, Toshiaki Makita wrote:
>> On 2019/08/16 0:21, 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.
>>
>> My intention is to make more people who want high speed network easily use XDP,
>> so making transparent XDP offload with current TC interface.
>>
>> What userspace program would monitor TC events with your suggestion?
> Have a new system daemon (xdpflowerd) that is independently
> packaged/shipped/installed. Anybody who wants accelerated TC can
> download/install it. OVS can be completely unaware of this.

Thanks, but that's what I called an unreliable solution...

>> ovs-vswitchd? If so, it even does not need to monitor TC. It can
>> implement XDP offload directly.
>> (However I prefer kernel solution. Please refer to "About alternative
>> userland (ovs-vswitchd etc.) implementation" section in the cover letter.)
>>
>> Also such a TC monitoring solution easily can be out-of-sync with real TC
>> behavior as TC filter/flower is being heavily developed and changed,
>> e.g. introduction of TC block, support multiple masks with the same pref, etc.
>> I'm not sure such an unreliable solution have much value.
> This same issue applies to the in-kernel implementation, isn't it?
> What happens if somebody sends patches for a new flower feature but
> doesn't add appropriate xdp support? Do we reject them?

Why can we accept a patch which breaks other in-kernel subsystem...
Such patches can be applied accidentally but we are supposed to fix such 
problems in -rc phase, aren't we?

Toshiaki Makita

  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
2019-08-16  1:09       ` Toshiaki Makita
2019-08-16 15:35         ` Stanislav Fomichev
2019-08-17 14:10           ` Toshiaki Makita [this message]
2019-08-15 15:46 ` William Tu
2019-08-16  1:38   ` Toshiaki Makita

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=11ab8890-f876-250e-1a52-eab0bf057640@gmail.com \
    --to=toshiaki.makita1@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=hawk@kernel.org \
    --cc=jakub.kicinski@netronome.com \
    --cc=jhs@mojatatu.com \
    --cc=jiri@resnulli.us \
    --cc=john.fastabend@gmail.com \
    --cc=kafai@fb.com \
    --cc=netdev@vger.kernel.org \
    --cc=sdf@fomichev.me \
    --cc=songliubraving@fb.com \
    --cc=u9012063@gmail.com \
    --cc=xiyou.wangcong@gmail.com \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org bpf@archiver.kernel.org
	public-inbox-index bpf


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/ public-inbox