Hello, On Fri, Jan 14, 2022 at 10:40:06AM +0100, Peter Zijlstra wrote: > You could do a special case sched_move_task(), that takes a css argument > instead of using the current task_css. Then for cgroups it looks like > nothing changes, but the scheduler will DTRT and act like it is in the > target cgroup. Then at the end, simply move it back to task_css. > > This obviously doesn't work for SoftIRQ accounting, but that is > 'special' anyway. Softirq stuff is not otherwise under scheduler > control and has preemption disabled. So, if this particular use case doesn't fit the backcharge model (I'm not sure yet). I'd much prefer it to maintain dynamic per-cgroup helper threads than move tasks around dynamically. Nothing else is using migration this way and we don't even need migration for seeding cgroups w/ CLONE_INTO_CGROUP. In the future, this should allow further optimizations and likely simplifications. It'd suck to have an odd exception usage. Thanks. -- tejun
