linux-kernel - Re: [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency

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Date:	Sat, 30 May 2015 13:30:23 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	svaidy@...ux.vnet.ibm.com
CC:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
	linuxppc-dev@...ts.ozlabs.org,
	Daniel Lezcano <daniel.lezcano@...aro.org>, rjw@...ysocki.net,
	linux-kernel@...r.kernel.org, anton@...ba.org,
	linux-pm@...r.kernel.org
Subject: Re: [PATCH] cpuidle: powernv/pseries: Decrease the snooze residency

On 05/30/2015 11:31 AM, Vaidyanathan Srinivasan wrote:
> * Preeti U Murthy <preeti@...ux.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.
> 

Oh Ok! Thanks for the clarification !

Regards
Preeti U Murthy
> --Vaidy
> 

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