Messages in this thread | | | Date | Wed, 30 Mar 2022 14:37:48 -0400 | From | Steven Rostedt <> | Subject | Re: [External] Re: [PATCH] sched/fair: fix broken bandwidth control with nohz_full |
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On Wed, 30 Mar 2022 20:23:27 +0200 Peter Zijlstra <peterz@infradead.org> wrote:
> > Chengming brought up VMs. That's a case to want to control the bandwidth, > > but also not interrupt them with timer interrupts when they are running as > > the top priority task on a CPU. > > It's CFS, there is nothing top priority about that.
If there's only one task running on a CPU, even with CFS, why do we need a tick?
Look, we have a host that is doing nothing but running VMs. Could be a single VM. The host doesn't even have disk, it just runs on from initrd, and the user is actually just logging into a guest.
Why should the host be triggering a tick when running this VM, which is the only thing that is running on the host? Yeah, it's CFS, or does CFS have to have a tick? even when there's nothing else on the CPU?
-- Steve
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