> From: Ananyev, Konstantin > Sent: Tuesday, June 6, 2017 4:29 PM > Subject: RE: [dpdk-dev] [RFCv2] service core concept > > > > From: Richardson, Bruce > > Sent: Tuesday, June 6, 2017 3:54 PM > > > > On Tue, Jun 06, 2017 at 11:25:57AM +0100, Van Haaren, Harry wrote: > > > > From: Ananyev, Konstantin > > > > Sent: Saturday, June 3, 2017 11:23 AM > > > > > > <snip>
<snip other discussion> > > > > > > There are a number of options here, each with its own merit: > > > > > > A) Services/cores config in EAL > > > Benefit is that service functionality can be transparent to the > > > application. Negative is > that the complexity is in EAL. > > > > > > B) Application configures services/cores > > > Benefit is no added EAL complexity. Negative is that application code has > > > to configure > cores (duplicated per application). > > > > > > > > > To answer this question, I think we need to estimate how many > > > applications would benefit > from EAL integration and balance that against > > the "complexity cost" of doing so. I do like the simplicity of option (B), > > however if there > is significant value in total transparency to the > > application I think (A) is the better choice. > > > > > > > > > Input on A) or B) welcomed! -Harry > > > > I'm definitely in favour of having it in EAL. The whole reason for doing > > this work is to make it easy for applications to dedicate cores to > > background tasks - including applications written before this > > functionality was added. By merging this into EAL, we can have > > transparency in the app, as we can have the service cores completely in > > the background, and the app can call rte_eal_mp_remote_launch() exactly > > as before, without unexpected failures. If we move this externally, the > > app needs to be reworked to take account of that fact, and call new, > > service-core aware, launch functions instead. > > Not sure I understood you here: > If the app don' plan to use any cores for services, it for sure will be able > to call > rte_eal_mp_remote_launch() as before (no services running case). Correct - EAL behavior remains unchanged if --service-cores=0xf is not passed > From other side, if the app would like to use services - it would need to > specify > which service it wants to run, and for each service provide a coremask, even > if > EAL already allocates service cores for it. See next paragraph > Or are you talking about the when EAL allocates service cores, and then > PMDs themselves (or EAL again) register their services on that cores? EAL could provide sane default behavior. For example, round-robin services over available service-cores. Multithread-capable services can be registered on all service cores. Its not a perfect solution for all service-to-core mapping problems, but I'd guess about 80% of cases would be covered: using a single service with a single service core dedicated to it :) > That's probably possible, but how PMD would know which service core(s) it > allowed to use? The PMD shouldn't be deciding - EAL for basic sanity config, or Application for advanced usage. > Things might get over-complicated here - in theory there could be multiple > PMDs, > each of them can have more than one service, running on multiple sets of > cores, etc. True - the NxM service:core mapping possibility can be huge - the API allows the application the flexibility if that flexibility is really required. If the flexibility is not required, the round-robin 1:1 service:core EAL scheme should cover it? -Harry
