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From: "Van Haaren, Harry" <harry.van.haaren@intel.com>
To: David Marchand <david.marchand@redhat.com>,
	mattias.ronnblom <mattias.ronnblom@ericsson.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH v2 1/2] service: add component useful work attribute
Date: Thu, 14 Jan 2021 12:15:42 +0000
Message-ID: <BYAPR11MB3143AF075065AF0F10E34FF9D7A80@BYAPR11MB3143.namprd11.prod.outlook.com> (raw)
In-Reply-To: <CAJFAV8zc-uM23DG-OviZdju9=Q2FdbezHLG=U7=EpUwV=5n5eQ@mail.gmail.com>

> -----Original Message-----
> From: David Marchand <david.marchand@redhat.com>
> Sent: Wednesday, January 13, 2021 2:43 PM
> To: Van Haaren, Harry <harry.van.haaren@intel.com>; mattias.ronnblom
> <mattias.ronnblom@ericsson.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v2 1/2] service: add component useful work
> attribute
> 
> Hello Harry, Mattias,
> 
> On Fri, Oct 16, 2020 at 2:57 PM Van Haaren, Harry
> <harry.van.haaren@intel.com> wrote:
> > > > > > On 2020-09-14 16:37, Harry van Haaren wrote:
> > > > > > > This commit adds a new attribute which allows the service to indicate
> > > > > > > if the previous iteration of work was "useful". Useful work here implies
> > > > > > > forward progress was made.
> > > > > >
> > > > > > > Exposing this information via an attribute to the application allows
> > > > > > > tracking of CPU cycles as being useful or not-useful, and a CPU load
> > > > > > > estimate can be deduced from that information.
> > > > > >
> > > > > >
> > > > > > How would that tracking be implemented? rte_service.c already keeps
> > > > > > track of the amount of busy cycles per service. Would it be possible to
> > > > > > reuse that mechanism to achieve the same goal?
> > > > >
> > > > > Tracking "busy cycles" is not exactly the same - Eventdev SW PMD can spend
> > > > > cycles polling, and trying to move packets around its internal queues, but
> > > make
> > > > > no forward progress. Measuring cycles spent in the service would not indicate
> > > > > the correct "busyness" in that case.
> > > > >
> > > > > In the suggested patchset, each service (e.g Eventdev SW PMD) can update
> > > > > a statistic itself, pushing an attribute value into the service-cores layer.
> > > > > This method allows each PMD to define "useful work" in its own way.
> > > > >
> > > > > > We did some prototyping on dynamic load balancing for the service core
> > > > > > framework, and then we extended the API is such a way that the service
> > > > > > callback would return a bool indicating if forward progress was made, if
> > > > > > I recall correctly. Sampling these counters allowed for tracking load on
> > > > > > both a per-lcore and per-service basis.
> > > > >
> > > > > The service callback return value can be stored/inspected on the service-core
> > > > > itself, but how to show that to the application? It still requires an attribute
> API
> > > > > like proposed below re-using "attr_get" API I think.
> > > > >
> > > > > So really the only difference in the prototype you mention is how the
> > > > > service itself communicates business to the service-cores infrastructure in
> > > EAL.
> > > > >
> > > > > Perhaps re-purposing return-value is simpler, but it limits statistics from the
> > > > > service to just business, and the API change requires all services to change.
> > > > >
> > > > > Pros of adding an API as this patchset proposes is to push attribute values to
> > > > > service-core in EAL is extensibility, and no API breakage.
> > > > >
> > > > > Given that context, Ack / push-back to this suggested approach?
> > >
> > > I need a conclusion.
> > > Is this required for 20.11?
> >
> > Given timeline - lets leave this until 21.02 release.
> > I think the above solution is adequate, but don't want to rush folks.
> >
> > Thanks for following up, chat next release. -Harry
> >
> 
> Did some discussion happen?
> 21.02-rc1 is coming soon.

Thanks for flagging, I'm not aware of any continuation of the discussions.
Mattias, do you have any updates?

This v2 currently fails to apply on a version.map file conflict, but otherwise is still fine IMO.

      reply	other threads:[~2021-01-14 12:15 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-07 16:21 [dpdk-dev] [PATCH " Harry van Haaren
2020-09-07 16:21 ` [dpdk-dev] [PATCH 2/2] event/sw: add useful work done attribute Harry van Haaren
2020-09-14  8:37 ` [dpdk-dev] [PATCH 1/2] service: add component useful work attribute David Marchand
2020-09-14 14:37   ` Van Haaren, Harry
2020-09-14 14:37 ` [dpdk-dev] [PATCH v2 " Harry van Haaren
2020-09-14 14:37   ` [dpdk-dev] [PATCH v2 2/2] event/sw: add useful work done attribute Harry van Haaren
2020-09-21 14:49   ` [dpdk-dev] [PATCH v2 1/2] service: add component useful work attribute David Marchand
2020-09-21 15:17     ` Van Haaren, Harry
2020-09-21 23:47     ` Honnappa Nagarahalli
2020-09-23 11:39   ` Mattias Rönnblom
2020-09-23 14:16     ` Van Haaren, Harry
2020-10-05 16:45       ` Van Haaren, Harry
2020-10-16 12:20         ` David Marchand
2020-10-16 12:57           ` Van Haaren, Harry
2021-01-13 14:42             ` David Marchand
2021-01-14 12:15               ` Van Haaren, Harry [this message]

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