> -----Original Message----- > From: David Marchand <david.march...@redhat.com> > Sent: Tuesday, July 28, 2020 3:53 PM > To: Matan Azrad <ma...@mellanox.com> > Cc: Xueming(Steven) Li <xuemi...@mellanox.com>; dev <dev@dpdk.org>; Asaf > Penso <as...@mellanox.com> > Subject: Re: [dpdk-dev] [PATCH] vdpa/mlx5: use master core Id for vhost > thread > > On Tue, Jul 28, 2020 at 9:30 AM Matan Azrad <ma...@mellanox.com> wrote: > > > > > rte_lcore_to_cpu_id(-1) is supposed to return the current lcore id. > > > > > As explained in the commitlog of 67ae5936c4fc36, for a non-EAL > > > > > thread (which has no associated lcore by default) calling this > > > > > function means lcore_config[-1].core_id. > > > > > > > > Deosn't lcore mean core? > > > > > > No. > > > > So, it may be that we have more than one lcore working on a specific cpu_id? > > Can you extend here? > > A control thread is a non-EAL thread.
Is the default thread a control thread? After eal init, rte_lcore_to_cpu_id(-1) returns 0. In function rte_ctrl_thread_create(), the new thread is set cpu affinity with control cpu set, bind it same core of default control thread. > A non-EAL thread has no lcore associated (unless you call the newly added > rte_thread_register API). > > Not sure why you need the physical core identifier in the driver. > > It is possible that non-EAL threads run on one physical core if you start your > application with the right cpuset. > But without checking, you can't make such an assumption. > > > > > > > > > > > So, if the private thread run on a core that opened by EAL, > > > > Shouldn't the API return the lcore of the private thread core? > > > > > > vhost-events is a control thread. > > > Was it working just by chance and returning 0 before? > > > > Probably yes. > > (gdb) info symbol &lcore_config[-1].core_id vfio_cfgs + 444820 in section .bss > of > /home/dmarchan/git/pub/dpdk.org/build/app/../lib/librte_eal.so.20.0 > > Please, update the commitlog. > Thanks. > > > -- > David Marchand
