From: Pablo Neira Ayuso <pablo@netfilter.org>
To: Edward Cree <ecree@solarflare.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>,
netdev <netdev@vger.kernel.org>, Jiri Pirko <jiri@resnulli.us>,
Cong Wang <xiyou.wangcong@gmail.com>
Subject: Re: TC stats / hw offload question
Date: Mon, 29 Apr 2019 21:14:50 +0200 [thread overview]
Message-ID: <20190429191450.kzhhe3zqnbt6f2ap@salvia> (raw)
In-Reply-To: <e30859ad-a4e9-b0fb-f37d-4e8dcf638fdb@solarflare.com>
On Mon, Apr 29, 2019 at 05:25:10PM +0100, Edward Cree wrote:
> On 29/04/2019 16:21, Pablo Neira Ayuso wrote:
> > On Mon, Apr 29, 2019 at 03:11:06PM +0100, Edward Cree wrote:
> >> This is a bit of a mess; the best idea I've got is for the
> >> TC_CLSFLOWER_STATS call to include a tcfa_index. Then the driver
> >> returns counter stats for that index, and tcf_exts_stats_update()
> >> only updates those actions whose index matches. But then
> >> fl_hw_update_stats() would have to iterate over all the indices in
> >> f->exts. What do you think?
> > You could extend struct flow_stats to pass an array of stats to the
> > driver, including one stats per action and the counter index. Then,
> > tcf_exts_stats_update() uses this array of stats to update per-action
> > stats.
> Yes, but that means allocating the flow_stats.stats array each time;
We use the stack to attach a reasonable size array, eg. 16 actions,
otherwise fall back to kmalloc(). I haven't seen any driver in the
tree supporting more than that so far.
> I'd rather avoid memory allocation unless it's necessary. As long as
> we can move the preempt_disable() inside the loop that's currently in
> tcf_exts_stats_update() (i.e. only disable pre-emption across each
> individual call to tcf_action_stats_update()) I think we can.
> I think I prefer my approach (ask for one tcfa_index at a time); but
> unmodified drivers that don't look at the passed index would return
> zeroes for actions after the first, so we'll need some way to handle
> those drivers separately (e.g. one tc_setup_cb_call with "answer
> this one if you don't do indices" and a bunch more with specified
> index values). I think that requires much less change to the
> existing drivers than putting an array back in the API, and keeps as
> much of the work as possible in the core where it won't have to be
> replicated in every driver.
That's all right. This chunk update will not be particularly large, so
we can change it anytime in the future.
> I'll put an RFC patch together soonish if no objections.
Sure, thanks.
prev parent reply other threads:[~2019-04-29 19:14 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-05 19:41 TC stats / hw offload question Edward Cree
2019-02-06 2:20 ` Jamal Hadi Salim
2019-02-08 10:26 ` Edward Cree
2019-02-09 17:39 ` Jamal Hadi Salim
2019-02-11 11:44 ` Edward Cree
2019-02-14 12:39 ` Jamal Hadi Salim
2019-02-14 15:17 ` Andy Gospodarek
2019-02-18 18:56 ` Edward Cree
2019-02-18 19:37 ` Edward Cree
2019-04-24 14:05 ` Edward Cree
2019-04-24 14:11 ` Pablo Neira Ayuso
2019-04-24 15:03 ` Edward Cree
2019-04-25 13:23 ` Edward Cree
2019-04-25 22:33 ` Pablo Neira Ayuso
2019-04-26 12:13 ` Edward Cree
2019-04-26 12:42 ` Jamal Hadi Salim
2019-04-26 18:49 ` Pablo Neira Ayuso
2019-04-29 14:11 ` Edward Cree
2019-04-29 15:21 ` Pablo Neira Ayuso
2019-04-29 16:25 ` Edward Cree
2019-04-29 19:14 ` Pablo Neira Ayuso [this message]
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