Re: [PATCH 2/4] timer: relax tick stop in idle entry

Jacob Pan
2015-11-16T23:41:43Z

On Mon, 16 Nov 2015 15:32:38 -0800
Arjan van de Ven <arjan@linux.intel.com> wrote:

> On 11/16/2015 3:28 PM, Paul E. McKenney wrote:
>
> > Is this mostly an special-purpose embedded thing, or do you expect
> > distros to be enabling this? If the former, I suggest
> > , but if distros are doing this for
> > general-purpose workloads, I instead suggest CONFIG_RCU_FAST_NO_HZ.
>
> thermal overload happens a lot on small devices, but sadly also in
> big datacenters where it is not uncommon to underprovision cooling
> capacity by a bit (it's one of those "99% of the time you only need
> THIS much, the 1% you need 30% more" and that more is expensive or
> even impractical)

CONFIG_RCU_FAST_NO_HZ is more inline with idle injection in that both
are targeted energy efficiency.
Checking ubuntu and fedora, seems both have CONFIG_RCU_NOCB_CPU_ALL=y.