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Date: Fri, 7 Jul 2017 01:16:09 +1000
From: Nicholas Piggin <npiggin@gmail.com>
To: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>, Michael Neuling
 <mikey@neuling.org>, Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>,
 Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>, "Rafael J. Wysocki"
 <rafael@kernel.org>, Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>,
 linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
 linux-pm@vger.kernel.org
Subject: Re: [PATCH 4/5] powernv:idle: Move initialization of sibling pacas
 to pnv_alloc_idle_core_states
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On Wed,  5 Jul 2017 22:08:15 +0530
"Gautham R. Shenoy" <ego@linux.vnet.ibm.com> wrote:

> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
> 
> On POWER9 DD1, in order to get around a hardware issue, we store in
> every CPU thread's paca the paca pointers of all its siblings.
> 
> Move this code into pnv_alloc_idle_core_states() soon after the space
> for saving the sibling pacas is allocated.
> 
> Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>

> -	if (cpu_has_feature(CPU_FTR_POWER9_DD1)) {
> -		int cpu;
> -
> -		pr_info("powernv: idle: Saving PACA pointers of all CPUs in their thread sibling PACA\n");
> -		for_each_possible_cpu(cpu) {
> -			int base_cpu = cpu_first_thread_sibling(cpu);
> -			int idx = cpu_thread_in_core(cpu);
> -			int i;
> -

You could move the thread_sibling_pacas allocation to here?

Speaking of which... core_idle_state and thread_sibling_pacas are
allocated with kmalloc_node... What happens if we take an SLB miss
in the idle wakeup code on these guys? Nothing good I think. Perhaps
we should put them into the pacas or somewhere in bolted memory.

Good cleanup though.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>