Thanks for the clarification, that makes sense to me now. It doesn't look like the patch handles CPU hotplugging though; a cpumask filled with *only* offline CPUs can be passed as a parameter, or all of the CPUs in the cpumask can be offlined after the setup is finished. This isn't a problem with the default behavior because num_possible_cpus() guarantees that there will always be at least one online CPU for the nvme queue (since the CPU hotplug code doesn't allow all CPUs to be offlined).
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1831566 Title: [realtime app] not possible to redirect drivers/nvme IRQs from realtime cpuset Status in linux package in Ubuntu: Confirmed Bug description: We're running realtime application on Ubuntu 16.04 with linux-image 4.15 and found it impossible to get rid of jitter introduced by Intel NVMe IRQs. I'm providing here a patch which solved the issue for us. The realtime application is bound to isolated CPUs (one thread per CPU, nohz_full= in kernel cmdline, all IRQs moved to housekeeping CPUs), application doesn't use any linux kernel syscalls except in startup phase so we don't expect any interruptions of the application from the kernel or HW. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1831566/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
