From: Ori Kam <orika@nvidia.com>
To: Ivan Malov <ivan.malov@arknetworks.am>,
"NBU-Contact-Thomas Monjalon (EXTERNAL)" <thomas@monjalon.net>
Cc: Rongwei Liu <rongweil@nvidia.com>, Matan Azrad <matan@nvidia.com>,
Slava Ovsiienko <viacheslavo@nvidia.com>,
Aman Singh <aman.deep.singh@intel.com>,
Yuying Zhang <yuying.zhang@intel.com>,
Ferruh Yigit <ferruh.yigit@amd.com>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
"dev@dpdk.org" <dev@dpdk.org>,
Raslan Darawsheh <rasland@nvidia.com>
Subject: RE: [PATCH v7] ethdev: add special flags when creating async transfer table
Date: Wed, 1 Feb 2023 14:29:03 +0000 [thread overview]
Message-ID: <MW2PR12MB46667289C4DBF3BB6071165FD6D19@MW2PR12MB4666.namprd12.prod.outlook.com> (raw)
In-Reply-To: <8456f29c-2b76-7f82-1f70-6ac9612df5f@arknetworks.am>
Hi Ivan,
> -----Original Message-----
> From: Ivan Malov <ivan.malov@arknetworks.am>
> Sent: Wednesday, 1 February 2023 16:04
>
> On Wed, 1 Feb 2023, Thomas Monjalon wrote:
>
> > 01/02/2023 12:50, Ivan Malov:
> >> On Wed, 1 Feb 2023, Thomas Monjalon wrote:
> >>> 31/01/2023 06:30, Ivan Malov:
> >>>> I still hope community will comment on the possibility to
> >>>> provide a hint mechanism for always-the-same match items,
> >>>> with the perspective of becoming more versatile.
> >>>
> >>> Any hint could be imagined.
> >>> But please keep this in mind: a hint is *not* a matching criteria,
> >>> for the simple reason that a hint can be ignored by the PMD.
> >>> So you cannot use a hint to avoid specifying a match item,
> >>> but you could use a hint to specify that an item is the same
> >>> for all the rules of a table.
> >>
> >> Reading the same thought expressed in your words, the penny drops.
> >> So, a hint then. But even not being a match criterion itself, it
> >> is still confined to knowledge about a too special particularity.
> >> If one needs to add similar hints for other aspects of matching,
> >> they will have to add more and more bits to this namespace.
> >> So why at all detach the namespace of hints from such of
> >> the match items? A more generic solution might be needed.
> >
> > The hints are not necessarily related to the matching.
> > That's why it is more flexible to have separate definitions.
>
> I hear ya.
>
> >
> >> In another email of yours, [1], you suggest that documentation be
> >> improved. But it seems that addressing the "fixed match" issue
> >> described by Ori (in the quote) could be that "more generic"
> >> approach. For example, if one added "always_fixed_spec" bit
> >> to struct rte_flow_item, this bit could be taken into
> >> account by PMD in rte_flow_pattern_template_create().
> >> When it has spotted this bit for item ANY_VPORT,
> >> it will treat it the way this "specialise" hint
> >> does, collecting the same upfront knowledge.
> >>
> >> Yes, I do acknowledge that encountering such a bit in
> >> a regular/sync flow parsing is irrelevant, but this
> >> is just a general idea and not the final proposal.
> >
> > Yes it does not have sense outside of template table.
>
> Yes, but something similar can be devised to attach
> some "always the same exact spec" meaning to given
> items in the pattern. Not necessarily via this bit.
>
We thought about it but it made the api to complex but we can revisit it.
I'm open to suggestions.
> >
> >> Also, in mail [2], Ori talks about separate pipelines
> >> for ingress and egress. That sheds some light on this
> >> hint, thanks. On the one hand, yes, vendors do tend
> >> to have separate pipelines for this, this and this,
> >> but, on the other hand, assuming this particular
> >> separation of pipelines and making a customised
> >> hint for it might not be quite generic. It is
> >> that special particularity which I am talking
> >> about in the first paragraph of my response.
> >>
> >> So why not combine addressing "fixed match" items
> >> and solving the problem of this "direction" hint?
> >
> > I agree we should try to better address templates
> > with some fixed matching items, but we could still need
> > to have some hints for other kind of optimizations.
>
> Agreed.
>
+1
> >
> >> Again, I can't come up with an immediate example
> >> of how precisely this could be useful, but since
> >> DPDK strives to being as much generic/neutral as
> >> possible, then why not consider this?
> >
> > I agree the hints may be quite vendor-specifics,
> > but they are optional and does not hurt vendors not implementing them.
> > For applications supporting many drivers,
> > they can use some hints without losing portability.
> >
> > So I don't think such approach is against genericity or neutrality,
> > it is just bringing some flexibility for the best performances.
> > And in DPDK, the first priority is the performance.
>
> I'm questioning this because I suspect that, had the original
> flow design had more flexibility / better decomposition,
> then perhaps it would have been unneeded to add these
> extra hints in the first instance. I don't mean to
> criticise them too much, though.
>
One of the problems is that the API is too flexible this means that
PMD must assume everything so it can't optimize, this is why we
need hints .
> >
> >> [1] https://mails.dpdk.org/archives/dev/2023-February/260667.html
> >> [2] https://mails.dpdk.org/archives/dev/2023-February/260668.html
> >>
> >>>> Other
> >>>> than that, your current patch might be OK, but, again,
> >>>> I think other reviewers' comments (if any) shall
> >>>> be addressed. But no strong objections from me.
> >>>>
> >>>> By the way, for this "specialise" field, in your opinion,
> >>>> which extra flags could emerge in future / would be nice
> >>>> to have? I mean, is there any concept of what can be
> >>>> added to this field's namespace and what can't be?
> >>>
> >>> I think there is no limit with hint flags to be added.
> >>> I repeat it again: hints can be ignored by the PMDs.
> >>
> >> Thank you.
> >
> > The template flow API is experimental and will probably remain as such
> > for a long time, so if you find a more elegant approach,
> > we will consider it.
>
> Thanks for explaining this.
>
> You know, now you mention it, are there non-debug app
> examples available that make use of this template API?
> Back in the day, I reviewed the template API, but
> since then, I've never come across any real-life
> examples. I'd appreciate you point something out.
>
> > But given we don't know how to make it better today,
> > and there is no real problem with its definition,
> > I don't see a reason to postpone its integration as experimental.
> >
> > In my opinion, having hint is good.
> > The real discussion is on the flags.
> > If we find how to manage the same optimization without these flags,
> > we could drop them, but the hint flexibility should remain.
> >
> >
> >
>
> Thank you.
next prev parent reply other threads:[~2023-02-01 14:29 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-07 2:40 [PATCH v1] ethdev: add direction info when creating the " Rongwei Liu
2022-09-11 8:22 ` Ori Kam
2022-09-12 16:57 ` Ivan Malov
2022-09-13 13:46 ` Rongwei Liu
2022-09-13 14:33 ` Ivan Malov
2022-09-14 5:16 ` Rongwei Liu
2022-09-14 7:32 ` Ivan Malov
2022-09-14 10:17 ` Rongwei Liu
2022-09-14 15:18 ` Ivan Malov
2022-09-14 21:02 ` Thomas Monjalon
2022-09-15 0:58 ` Rongwei Liu
2022-09-15 7:47 ` Ivan Malov
2022-09-15 8:18 ` Thomas Monjalon
2022-09-15 9:42 ` Ivan Malov
2022-09-15 8:48 ` Rongwei Liu
2022-09-15 10:59 ` Ivan Malov
2022-09-15 11:16 ` Thomas Monjalon
2022-09-20 9:41 ` Ori Kam
2022-09-20 12:45 ` Ivan Malov
2022-09-20 13:59 ` Ori Kam
2022-09-20 15:28 ` Ivan Malov
2022-09-21 7:34 ` Ori Kam
2022-09-21 8:39 ` Andrew Rybchenko
2022-09-21 9:04 ` Ivan Malov
2022-09-21 9:40 ` Thomas Monjalon
2022-09-21 10:04 ` Andrew Rybchenko
2022-09-21 12:41 ` Ori Kam
2022-09-21 12:51 ` Morten Brørup
2022-09-22 7:39 ` Andrew Rybchenko
2022-09-22 10:06 ` Ori Kam
2022-09-22 10:31 ` Andrew Rybchenko
2022-09-22 13:00 ` Ori Kam
2022-09-23 7:25 ` Andrew Rybchenko
2022-09-23 16:11 ` Ori Kam
2022-09-22 12:43 ` Ivan Malov
2022-09-22 14:46 ` Ori Kam
2022-09-28 9:24 ` [PATCH v3] ethdev: add hint when creating async " Rongwei Liu
2022-10-04 8:31 ` Andrew Rybchenko
2022-11-04 10:42 ` [PATCH v4] ethdev: add special flags " Rongwei Liu
2022-11-04 10:44 ` Rongwei Liu
2022-11-08 11:39 ` Andrew Rybchenko
2022-11-08 11:47 ` Andrew Rybchenko
2022-11-08 13:29 ` Thomas Monjalon
2022-11-08 14:38 ` Andrew Rybchenko
2022-11-08 15:25 ` Thomas Monjalon
2022-11-09 8:53 ` Andrew Rybchenko
2022-11-09 9:03 ` Thomas Monjalon
2022-11-09 9:36 ` Andrew Rybchenko
2022-11-09 10:50 ` Thomas Monjalon
2022-11-06 10:02 ` [PATCH v3] ethdev: add hint " Andrew Rybchenko
2022-11-07 1:58 ` Rongwei Liu
2022-11-08 9:19 ` Thomas Monjalon
2022-11-08 9:35 ` Andrew Rybchenko
2022-11-08 11:18 ` Thomas Monjalon
2022-11-08 11:48 ` Andrew Rybchenko
2022-11-14 8:47 ` [PATCH v6] ethdev: add special flags " Rongwei Liu
2022-11-14 11:59 ` [PATCH v7] " Rongwei Liu
2023-01-17 15:13 ` Ferruh Yigit
2023-01-17 17:01 ` Ferruh Yigit
2023-01-18 2:50 ` Rongwei Liu
2023-01-18 7:30 ` Andrew Rybchenko
2023-01-18 7:28 ` Andrew Rybchenko
2023-01-18 16:18 ` Thomas Monjalon
2023-02-01 10:17 ` Andrew Rybchenko
2023-02-01 10:58 ` Thomas Monjalon
2023-02-01 11:10 ` Andrew Rybchenko
2023-02-01 11:18 ` Thomas Monjalon
2023-02-01 11:38 ` Andrew Rybchenko
2023-02-01 13:48 ` Thomas Monjalon
2023-02-02 9:21 ` Andrew Rybchenko
2023-02-02 11:29 ` Thomas Monjalon
2023-02-02 12:24 ` Andrew Rybchenko
2023-02-01 11:22 ` Ori Kam
2023-02-01 11:29 ` Andrew Rybchenko
2023-02-01 11:12 ` Ori Kam
2023-02-01 11:20 ` Thomas Monjalon
2023-01-30 0:00 ` Ivan Malov
2023-01-30 2:34 ` Rongwei Liu
2023-01-30 7:40 ` Ivan Malov
2023-01-30 14:49 ` Rongwei Liu
2023-01-30 23:00 ` Ivan Malov
2023-01-31 3:06 ` Rongwei Liu
2023-01-31 5:30 ` Ivan Malov
2023-01-31 6:14 ` Rongwei Liu
2023-02-01 10:12 ` Thomas Monjalon
2023-02-01 11:50 ` Ivan Malov
2023-02-01 13:37 ` Thomas Monjalon
2023-02-01 14:04 ` Ivan Malov
2023-02-01 14:23 ` Thomas Monjalon
2023-02-01 14:29 ` Ori Kam [this message]
2023-02-02 11:19 ` [PATCH v8] ethdev: add optimization hints in flow template table Rongwei Liu
2023-02-02 11:33 ` Thomas Monjalon
2023-02-08 23:19 ` Ferruh Yigit
2022-11-09 8:11 ` [PATCH v5] ethdev: add special flags when creating async transfer table Rongwei Liu
2022-11-09 8:13 ` Rongwei Liu
2022-11-09 8:31 ` Thomas Monjalon
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