On Thu, Jan 28, 2021 at 09:01:37PM +0100, Thomas Gleixner wrote: > On Thu, Jan 28 2021 at 13:59, Marcelo Tosatti wrote: > >> The whole pile wants to be reverted. It's simply broken in several ways. > > > > I was asking for your comments on interaction with CPU hotplug :-) > > Which I answered in an seperate mail :) > > > So housekeeping_cpumask has multiple meanings. In this case: > > ... > > > So as long as the meaning of the flags are respected, seems > > alright. > > Yes. Stuff like the managed interrupts preference for housekeeping CPUs > when a affinity mask spawns housekeeping and isolated is perfectly > fine. It's well thought out and has no limitations. > > > Nitesh, is there anything preventing this from being fixed > > in userspace ? (as Thomas suggested previously). > > Everything with is not managed can be steered by user space. Yes, but it seems to be racy (that is, there is a window where the interrupt can be delivered to an isolated CPU). ethtool -> xgbe_set_channels -> xgbe_full_restart_dev -> xgbe_alloc_memory -> xgbe_alloc_channels -> cpumask_local_spread Also ifconfig eth0 down / ifconfig eth0 up leads to cpumask_spread_local. How about adding a new flag for isolcpus instead?
