From: Paul Mackerras <paulus@samba.org>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: svaidyan@in.ibm.com, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org, srivatsa.bhat@linux.vnet.ibm.com
Subject: Re: [PATCH 2/6] powerpc, powernv, CPU hotplug: Put offline CPUs in Fast-Sleep instead of Nap
Date: Thu, 5 Jun 2014 14:23:36 +1000 [thread overview]
Message-ID: <20140605042336.GA3199@drongo> (raw)
In-Reply-To: <20140528043856.15676.35844.stgit@preeti.in.ibm.com>
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.
...
> 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.
WARNING: multiple messages have this Message-ID (diff)
From: Paul Mackerras <paulus@samba.org>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: benh@kernel.crashing.org, linux-kernel@vger.kernel.org,
svaidyan@in.ibm.com, srivatsa.bhat@linux.vnet.ibm.com,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/6] powerpc, powernv, CPU hotplug: Put offline CPUs in Fast-Sleep instead of Nap
Date: Thu, 5 Jun 2014 14:23:36 +1000 [thread overview]
Message-ID: <20140605042336.GA3199@drongo> (raw)
In-Reply-To: <20140528043856.15676.35844.stgit@preeti.in.ibm.com>
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.
...
> 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.
next prev parent reply other threads:[~2014-06-05 4:23 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-28 4:38 [PATCH 0/6] ppc, kvm, cpuidle: Allow offline and kvm standby threads to enter fastsleep Preeti U Murthy
2014-05-28 4:38 ` [PATCH 1/6] powernv, cpuidle: Move the flags used for idle state discovery to powernv core Preeti U Murthy
2014-05-28 4:38 ` [PATCH 2/6] powerpc, powernv, CPU hotplug: Put offline CPUs in Fast-Sleep instead of Nap Preeti U Murthy
2014-06-05 4:23 ` Paul Mackerras [this message]
2014-06-05 4:23 ` Paul Mackerras
2014-05-28 4:39 ` [PATCH 3/6] KVM: PPC: Book3S HV: Enable CPUs to run guest after waking up from fast-sleep Preeti U Murthy
2014-05-28 4:39 ` [PATCH 4/6] KVM: PPC: Book3S HV: Consolidate the idle-state enter sequence in KVM Preeti U Murthy
2014-05-28 4:39 ` [PATCH 5/6] KVM: PPC: Book3S HV: Put KVM standby hwthreads to fast-sleep instead of nap Preeti U Murthy
2014-05-28 4:39 ` [PATCH 6/6] ppc, book3s: Go back to same idle state after handling machine check interrupt Preeti U Murthy
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