From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: linux-pm@vger.kernel.org,
Daniel Lezcano <daniel.lezcano@linaro.org>,
rjw@rjwysocki.net, linux-kernel@vger.kernel.org, anton@samba.org,
Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency
Date: Sat, 30 May 2015 11:31:41 +0530 [thread overview]
Message-ID: <20150530060141.GA19134@dirshya.in.ibm.com> (raw)
In-Reply-To: <55686DE5.6010001@linux.vnet.ibm.com>
* Preeti U Murthy <preeti@linux.vnet.ibm.com> [2015-05-29 19:17:17]:
[snip]
> > + if (max_idle_state > 1) {
> > + snooze_timeout_en = true;
> > + snooze_timeout = cpuidle_state_table[1].target_residency *
> > + tb_ticks_per_usec;
> > + }
>
> Any idea why we don't have snooze defined on the shared lpar configuration ?
In shared lpar case, spinning in guest context may potentially take
away cycles from other lpars waiting to run on the same physical cpu.
So the policy in shared lpar case is to let PowerVM hypervisor know
immediately that the guest cpu is idle which will allow the hypervisor
to use the cycles for other tasks/lpars.
--Vaidy
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WARNING: multiple messages have this Message-ID (diff)
From: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
To: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org,
Daniel Lezcano <daniel.lezcano@linaro.org>,
rjw@rjwysocki.net, linux-kernel@vger.kernel.org, anton@samba.org,
linux-pm@vger.kernel.org
Subject: Re: [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency
Date: Sat, 30 May 2015 11:31:41 +0530 [thread overview]
Message-ID: <20150530060141.GA19134@dirshya.in.ibm.com> (raw)
In-Reply-To: <55686DE5.6010001@linux.vnet.ibm.com>
* Preeti U Murthy <preeti@linux.vnet.ibm.com> [2015-05-29 19:17:17]:
[snip]
> > + if (max_idle_state > 1) {
> > + snooze_timeout_en = true;
> > + snooze_timeout = cpuidle_state_table[1].target_residency *
> > + tb_ticks_per_usec;
> > + }
>
> Any idea why we don't have snooze defined on the shared lpar configuration ?
In shared lpar case, spinning in guest context may potentially take
away cycles from other lpars waiting to run on the same physical cpu.
So the policy in shared lpar case is to let PowerVM hypervisor know
immediately that the guest cpu is idle which will allow the hypervisor
to use the cycles for other tasks/lpars.
--Vaidy
next prev parent reply other threads:[~2015-05-30 6:01 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-29 12:32 [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency Shilpasri G Bhat
2015-05-29 13:47 ` Preeti U Murthy
2015-05-30 6:01 ` Vaidyanathan Srinivasan [this message]
2015-05-30 6:01 ` Vaidyanathan Srinivasan
2015-05-30 8:00 ` Preeti U Murthy
2015-05-31 1:38 ` Benjamin Herrenschmidt
2015-06-03 15:35 ` Vaidyanathan Srinivasan
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