Ok thanks
> -----Original Message----- > From: Bruce Richardson <bruce.richard...@intel.com> > Sent: Monday, October 21, 2019 7:26 PM > To: Varghese, Vipin <vipin.vargh...@intel.com> > Cc: Loftus, Ciara <ciara.lof...@intel.com>; 'Stephen Hemminger' > <step...@networkplumber.org>; 'dev@dpdk.org' <dev@dpdk.org>; Ye, > Xiaolong <xiaolong...@intel.com>; Laatz, Kevin <kevin.la...@intel.com>; > Yigit, Ferruh <ferruh.yi...@intel.com> > Subject: Re: [dpdk-dev] [PATCH v2 2/3] net/af_xdp: support pinning of IRQs > > 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
