Re: [Xen-devel] [PATCH v3 3/6] xen: RCU/x86/ARM: discount CPUs that were idle when grace period started.

On 08/18/2017 07:04 PM, Dario Faggioli wrote: > Xen is a tickless (micro-)kernel, i.e., when a CPU becomes > idle there is no timer tick that will periodically wake the > CPU up. > OTOH, when we imported RCU from Linux, Linux was (on x86) a > ticking kernel, i.e., there was a periodic timer tick

Re: [Xen-devel] [PATCH v3 3/6] xen: RCU/x86/ARM: discount CPUs that were idle when grace period started.

Il 22 Ago 2017 14:59, Jan Beulich ha scritto: >>> On 18.08.17 at 20:04, wrote: > Changes from v2: > * initialize idle_cpumask to "all clear", i.e., all the CPUs are busy; > they'll clear their bit out themselves as soon as the run the idle > loop

Re: [Xen-devel] [PATCH v3 3/6] xen: RCU/x86/ARM: discount CPUs that were idle when grace period started.

>>> On 18.08.17 at 20:04, wrote: > Changes from v2: > * initialize idle_cpumask to "all clear", i.e., all the CPUs are busy; > they'll clear their bit out themselves as soon as the run the idle > loop (pretty soon anyway). Just to make sure I correctly understand

[Xen-devel] [PATCH v3 3/6] xen: RCU/x86/ARM: discount CPUs that were idle when grace period started.

Xen is a tickless (micro-)kernel, i.e., when a CPU becomes idle there is no timer tick that will periodically wake the CPU up. OTOH, when we imported RCU from Linux, Linux was (on x86) a ticking kernel, i.e., there was a periodic timer tick always running, even on idle CPUs. This was bad for power