> -----Original Message----- > From: David Marchand <david.march...@redhat.com> > Sent: Wednesday, January 13, 2021 2:43 PM > To: Van Haaren, Harry <harry.van.haa...@intel.com>; mattias.ronnblom > <mattias.ronnb...@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.haa...@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.
