Re: TC stats / hw offload question

From: Edward Cree <ecree@solarflare.com>
To: Jamal Hadi Salim <jhs@mojatatu.com>, netdev <netdev@vger.kernel.org>
Cc: Jiri Pirko <jiri@resnulli.us>,
	Cong Wang <xiyou.wangcong@gmail.com>,
	"Or Gerlitz" <gerlitz.or@gmail.com>,
	Andy Gospodarek <andy@greyhouse.net>,
	"PJ Waskiewicz" <pjwaskiewicz@gmail.com>,
	Anjali Singhai Jain <anjali.singhai@intel.com>,
	Jakub Kicinski <jakub.kicinski@netronome.com>
Subject: Re: TC stats / hw offload question
Date: Mon, 11 Feb 2019 11:44:35 +0000	[thread overview]
Message-ID: <11ab2dc0-ec39-18cd-d170-0d5f954198b9@solarflare.com> (raw)
In-Reply-To: <561205a6-101b-c86b-e77d-6ebdcf31a56d@mojatatu.com>

On 09/02/19 17:39, Jamal Hadi Salim wrote:
> On 2019-02-08 5:26 a.m., Edward Cree wrote:
>>   I can't find any stats counters on
>>   the "match" either in the software path or the offload API.
>
> Hasnt been necessary thus far.
> Is your end goal to match and count?
My end goal is to implement TC offload in some hw we're designing
 here at Solarflare.  So I'm trying to determine what hardware is
 expected/required to do.
It might be possible to design our new hw so that we can attach a
 counter to every action, if that's what TC wants.  But since the
 other vendors don't seem to do that, I wondered if there was a
 reason, or if perhaps the counter resources (and PCI bw to read
 them) could be saved if all those separate counters aren't really
 needed.  Right now the design we are considering would only count
 packets as-matched, i.e. before any edits.  That's fine for encap
 — you can calculate the bytes correction in SW — but not for decap
 since in principle the length of the RXed outer headers could
 vary (e.g. you might have IP options there).

-Ed