Messages in this thread | | | Date | Thu, 5 Jun 2014 14:23:36 +1000 | From | Paul Mackerras <> | Subject | Re: [PATCH 2/6] powerpc, powernv, CPU hotplug: Put offline CPUs in Fast-Sleep instead of Nap |
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On Wed, May 28, 2014 at 10:08:56AM +0530, Preeti U Murthy wrote: > From: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com> > > The offline cpus are put to fast sleep if the idle state is discovered in the > device tree. This is to gain maximum powersavings in the offline state.
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> while (!generic_check_cpu_restart(cpu)) { > ppc64_runlatch_off(); > - power7_nap(); > + > + /* If sleep is supported, go to sleep, instead of nap */ > + if (idle_states & IDLE_USE_SLEEP) > + power7_sleep(); > + else > + power7_nap(); > + > ppc64_runlatch_on(); > if (!generic_check_cpu_restart(cpu)) { > DBG("CPU%d Unexpected exit while offline !\n", cpu);
What is the latency for waking up from fast sleep state? I'm concerned this will increase the latency for entering KVM guests.
Paul.
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