> -----Original Message----- > From: Bruce Richardson <bruce.richard...@intel.com> > Sent: Tuesday, February 16, 2021 5:31 PM > To: Van Haaren, Harry <harry.van.haa...@intel.com> > Cc: Burakov, Anatoly <anatoly.bura...@intel.com>; dev@dpdk.org > Subject: Re: [dpdk-dev] [PATCH] eal: support using 0 as coremask for no- > affinitization > > On Tue, Feb 16, 2021 at 05:22:25PM +0000, Van Haaren, Harry wrote: > > > -----Original Message----- > > > From: Burakov, Anatoly <anatoly.bura...@intel.com> > > > Sent: Tuesday, February 16, 2021 10:53 AM > > > To: Richardson, Bruce <bruce.richard...@intel.com>; Van Haaren, Harry > > > <harry.van.haa...@intel.com> > > > Cc: dev@dpdk.org > > > Subject: Re: [dpdk-dev] [PATCH] eal: support using 0 as coremask for no- > > > affinitization > > > > > > On 16-Feb-21 10:46 AM, Bruce Richardson wrote: > > > > On Tue, Feb 16, 2021 at 10:36:13AM +0000, Burakov, Anatoly wrote: > > > >> On 16-Feb-21 9:43 AM, Bruce Richardson wrote: > > > >>> Allow the user to specify that they don't want any core pinning from > DPDK > > > >>> by passing in the coremask of 0. > > > >>> --- > > > >> > > > >> I haven't checked what happens yet, but down the line we also set > > > >> affinity > > > >> for service cores as well as interrupt thread. what would be the > > > >> semantics > > > >> of those in this particular case? do we want the same ability for > > > >> service > > > >> cores (i.e. pick a non-affinitized core)? And where does interrupt > > > >> thread > > > >> affinitize in this case (presumably, nowhere too)? > > > >> > > > > I have not checked the service core setup, because a) I forgot about > > > > them > > > > and b) I'm not sure how their affinity rules work with respect to the > > > > main > > > > lcore mask. On the other hand I did check out that the lcore mask for > > > > all > > > > non-pinned threads, or control threads, is the full set of bits as > > > > expected. > > > > > > > > /Bruce > > > > > > > > > > +Harry, > > > > > > I believe service core mask must not overlap with lcore masks, so > > > presumably using 0 as lcore mask would make it so that any service core > > > mask will be valid (which is presumably what we want?). > > > > Services cores -S list or -s <mask> *must* overlap with the RTE lcores, EAL > > then"steals" the service cores from the application lcores, code that > implements here: > > http://git.dpdk.org/dpdk- > stable/tree/lib/librte_eal/common/eal_common_options.c?h=20.11#n657 > > > > > Should service cores also have a "just pick a core" parameter? > > > > I'm not sure, depends on what the bigger goal is here. > > Assuming we're enabling this for ROLE_RTE threads, then > > it would seem to me that ROLE_SERVICE and control threads > > would require similar treatment? > > > Control threads are affinitised to all cores not in the coremask, which > means in this case that they can run anywhere on the system the OS chooses.
Ah ok, fair enough yes. > In case of service cores, it would seem that using service cores with an > empty coremask is just not compatible. I would assume that this > incompatibility already exists when one has a coremask with only one core > already in it. Yes, correct, it would leave zero lcores for ROLE_RTE, meaning no lcores for the application. A possible solution would be to special case a zero service core mask and apply the same treatment as ROLE_RTE coremask? Others likely have better ideas - I don't have time to follow DPDK threading/pinning topic closely at the moment.
