From: Jiri Pirko <jiri@resnulli.us>
To: Jakub Kicinski <kubakici@wp.pl>
Cc: netdev@vger.kernel.org, mlxsw@mellanox.com,
Daniel Borkmann <daniel@iogearbox.net>,
Simon Horman <simon.horman@netronome.com>
Subject: Re: nfp bpf offload add/replace
Date: Thu, 7 Sep 2017 16:05:03 +0200 [thread overview]
Message-ID: <20170907140503.GE1967@nanopsycho> (raw)
In-Reply-To: <20170907144412.7a4a7cf7@cakuba.netronome.com>
Thu, Sep 07, 2017 at 03:44:12PM CEST, kubakici@wp.pl wrote:
>On Thu, 7 Sep 2017 11:10:33 +0200, Jiri Pirko wrote:
>> Hi Kuba.
>>
>> I'm looking into cls_bpf code and nfp_net_bpf_offload function in your
>> driver. Why do you need TC_CLSBPF_ADD? Seems like TC_CLSBPF_REPLACE
>> should be enough. It would make the cls_bpf code easier.
>>
>> Note that other cls just have replace/destroy (u32 too, as drivers
>> handle NEW/REPLACE in one switch-case - will patch this).
>
>Could we clarify what the REPLACE is actually supposed to do? :)
>
>In the flower code and the REPLACE looks a lot like ADD on the
>surface... If change is called it will invoke REPLACE with the new
>filter and then if there was an old filter, it will do DELETE. Is my
>understanding correct?
Yes, correct.
>
>If so I found this model of operation somehow confusing. Plus the
>management of flows may get slightly tricky if there is a possibility of
>"replacing" a flow with an identical one. Flower may make calls like
>these:
>
>add flower vlan_id 100 action ...
># REPLACE vid 100 ...
>change ... flower vlan_id 100 action ...
># REPLACE vid 100 ...
># DELETE vid 100 ...
Yes, that is the flow.
>
>Doesn't this force driver/HW to implement refcounting on the rules?
Why do you think so? There is a cookie that is passed from flower down
and driver uses it to remove the entry.
>
>On why I need the replace - BPF unlike other classifiers usually
>installs a single program, I think offloading multiple TC filters is
>questionable (people will use tailcalls instead most likely). I want to
>be able to implement atomic replace of that single program (i.e. not ADD
>followed by DELETE) because that simplifies the driver quite a bit.
Understood. So, looks like the REPLACE/DESTROY would be sufficient for
bpf. ADD is not needed as it can be done by REPLACE-NULL, right?
On the other hand, the rest of the cls, namely flower, u32 and matchall
need ADD/DESTROY as they don't really do no replacing.
Makes sense?
next prev parent reply other threads:[~2017-09-07 14:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 9:10 nfp bpf offload add/replace Jiri Pirko
2017-09-07 13:44 ` Jakub Kicinski
2017-09-07 14:05 ` Jiri Pirko [this message]
2017-09-07 16:52 ` Jakub Kicinski
Reply instructions:
You may reply publicly 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=20170907140503.GE1967@nanopsycho \
--to=jiri@resnulli.us \
--cc=daniel@iogearbox.net \
--cc=kubakici@wp.pl \
--cc=mlxsw@mellanox.com \
--cc=netdev@vger.kernel.org \
--cc=simon.horman@netronome.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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).