On 29.07.19 19:30, Paolo Bonzini wrote:
On 29/07/19 17:08, Steven Rostedt wrote:
On Sun, 28 Jul 2019 11:06:50 +0200
Juergen Gross <[email protected]> wrote:
In case we'd want to change that I'd rather not special case timers, but
apply a more general solution to the quite large amount of similar
cases: I assume the majority of cpu_relax() uses are affected, so adding
a paravirt op cpu_relax() might be appropriate.
That could be put under CONFIG_PARAVIRT_SPINLOCK. If called in a guest
it could ask the hypervisor to give up the physical cpu voluntarily
(in Xen this would be a "yield" hypercall).
Seems paravirt wants our cpu_chill() ;-)
Actually that is not really a joke! :)
As CONFIG_PARAVIRT is no longer so massive intrusive as some time ago
it might really be worth thinking of.
From Xen perspective I'd really like a way to give up the vcpu instead
of doing a busy wait. And having another user and (even better) already
some patches addressing some (or all?) callsites sounds like a win-win
situation for me.
So +1 from me for cpu_chill() via a new paravirt op.
Juergen
