On Fri, Apr 05, 2019 at 04:23:27PM -0600, Jens Axboe wrote: > On 4/5/19 3:59 PM, Keith Busch wrote: > > Managed interrupts can not migrate affinity when their CPUs are offline. > > If the CPU is allowed to shutdown before they're returned, commands > > dispatched to managed queues won't be able to complete through their > > irq handlers. > > > > Introduce per-hctx reference counting so we can block the CPU dead > > notification for all allocated requests to complete if an hctx's last > > CPU is being taken offline. > > What does this do to performance? We're doing a map per request...
It should be the same cost as the blk_queue_enter/blk_queue_exit that's also done per request, which is pretty cheap way to count users. I don't think I'm measuring a difference, but my test sample size so far is just one over-powered machine.
