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From: Jamal Hadi Salim <jhs@mojatatu•com>
To: John Fastabend <john.fastabend@gmail•com>,
	jiri@resnulli•us, daniel@iogearbox•net
Cc: netdev@vger•kernel.org, alexei.starovoitov@gmail•com,
	davem@davemloft•net
Subject: Re: [net-next PATCH 3/4] net: sched: cls_u32 add bit to specify software only rules
Date: Thu, 25 Feb 2016 07:56:35 -0500	[thread overview]
Message-ID: <56CEFA03.3080802@mojatatu.com> (raw)
In-Reply-To: <56CE7D37.9000701@gmail.com>

On 16-02-24 11:04 PM, John Fastabend wrote:
> On 16-02-24 05:31 AM, Jamal Hadi Salim wrote:

> I think this is absolutely necessary not only for performance of
> reporting the rules back to software but if we don't do it generically
> the driver will have to do it anyways because doing the inverse
> transformation from hw implementation to u32 is really tricky and in
> fact with hnodes and knodes there are multiple cls_u32 "programs" that
> functionally are the same so we have no way to return what the user
> actually programmed without it. Further eBPF (the next classifier I'm
> working on) is even worse in this regard.

Ok, I guess there are multiple use cases for it ;->
Yes, with ebpf it will be worse because data and instructions are
inter- mingled (and our interest is in data only). Note:
Over the years this has been a big struggle for human
friendliness. I thought we didnt care about humans (as in automation)
but you are saying this will affect machines too ;-> We cant allow
that ;->

Note: You could decode u32 descriptions but it is an involved effort.
Example, see this feature in tc:
---
jhs@jhs1 tc -pretty filter ls dev $ETH parent ffff: protocol ip
filter pref 11 u32
filter pref 11 u32 fh 800: ht divisor 1
filter pref 11 u32 fh 800::800 order 2048 key ht 800 bkt 0 flowid 1:1
   match IP src 10.0.0.130/32
	action order 1: gact action drop
	 random type none pass val 0
	 index 1 ref 1 bind 1
----
See that "match" field reading in anglais? It requires more and more
additions of pretty printers that translate back.

What about adding some tag to allow for easy "babel translation"?

> You can see my solution to
> this "load in hardware" filter list in patch 4/4. See Jiri's comment
> also on that and see if you agree.

Ok, will do.

cheers,
jamal

  reply	other threads:[~2016-02-25 12:56 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-02-23 19:02 [net-next PATCH 1/4] net: sched: consolidate offload decision in cls_u32 John Fastabend
2016-02-23 19:02 ` [net-next PATCH 2/4] net: cls_u32: move TC offload feature bit into cls_u32 offload logic John Fastabend
2016-02-24  6:12   ` Simon Horman
2016-02-24 13:21   ` Jamal Hadi Salim
2016-02-23 19:03 ` [net-next PATCH 3/4] net: sched: cls_u32 add bit to specify software only rules John Fastabend
2016-02-23 22:29   ` Samudrala, Sridhar
2016-02-23 23:30     ` John Fastabend
2016-02-24  6:11   ` Simon Horman
2016-02-24  7:24     ` John Fastabend
2016-02-24  8:04   ` Amir Vadai"
2016-02-24  8:40     ` Jiri Pirko
2016-02-24  8:55       ` John Fastabend
2016-02-24  9:29         ` Jiri Benc
2016-02-25  4:09           ` John Fastabend
2016-02-25 13:19             ` Jamal Hadi Salim
2016-02-25 16:39               ` John Fastabend
2016-02-24 13:31   ` Jamal Hadi Salim
2016-02-25  4:04     ` John Fastabend
2016-02-25 12:56       ` Jamal Hadi Salim [this message]
2016-02-25 21:56         ` John Fastabend
2016-02-25 23:05           ` Jamal Hadi Salim
2016-02-25 23:08             ` John Fastabend
2016-02-23 19:03 ` [net-next PATCH 4/4] net: sched: create hardware only classifier filter John Fastabend
2016-02-24  8:47   ` Jiri Pirko
2016-02-25 13:14     ` Jamal Hadi Salim
2016-02-25 17:36       ` John Fastabend
2016-02-24  6:12 ` [net-next PATCH 1/4] net: sched: consolidate offload decision in cls_u32 Simon Horman
2016-02-24  8:49 ` Jiri Pirko
2016-02-24 13:20 ` Jamal Hadi Salim

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