On Mon, Oct 21, 2019 at 02:45:05PM +0100, Varghese, Vipin wrote: > Hi Bruce, > > snipped > > > This ability to have the driver pin the interrupts for the > > > > user would be a big timesaver for developers too, who may be > > > > constantly re- running apps when testing. > > > Here my understanding, user can not or should not pass DPDK cores for > > interrupt pinning. So should we ask the driver to fetch > > `rte_eal_configuration` > > and ensure the same? > > > > > > > Actually I disagree. I think the user should pass the cores for interrupt > > pinning, > I agree to this. > > > because unlike other PMDs it is perfectly valid to have the interrupts > > pinned to > > dedicated cores separate from those used by DPDK. > My point is the same, but not on DPDK DP or service cores. > > > > > Or taking another example, suppose the app takes 8 cores in the coremask, > > but > > only one of those cores is to be used for I/O, what cores should the driver > > pin > > the interrupts to? > It can be cores on machine (guest or host) which is not used by DPDK. > > It probably should be the same core used for I/O, but the > > driver can't know which cores will be for that, or alternatively the user > > might > > want to use AF_XDP split across two cores, in which case any core on the > > system might be the intended one for interrupts. > I agree to the patch, only difference in dev->probe function, should not > there be validation to ensure the IRQ core is not DPDK core or Service core > as the Interface is owned by kernel and for non matched eBPF skb buff is used > by kernel. > No. Since the 5.4 kernel, it's a usable configuration to run both the kernel and userspace portions of AF_XDP on the same core. In order to get best performance with a fixed number of cores, this setup - with interrupts pinned to the polling RX core - is now recommended. [For absolute best perf using any number of cores, a separate interrupt core may still work best, though]
/Bruce
