linux-kernel - Re: [PATCH v1 1/6] x86/resctrl: Move __resctrl_sched

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Message-ID: <d40b3d06-b0b9-40c2-a7bb-19e19d5a3803@intel.com>
Date: Mon, 8 Apr 2024 20:53:53 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Peter Newman <peternewman@...gle.com>
CC: Fenghua Yu <fenghua.yu@...el.com>, James Morse <james.morse@....com>,
	Stephane Eranian <eranian@...gle.com>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, <x86@...nel.org>, "H. Peter Anvin"
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Subject: Re: [PATCH v1 1/6] x86/resctrl: Move __resctrl_sched_in() out-of-line

Hi Peter,

On 4/8/2024 2:41 PM, Peter Newman wrote:
> On Mon, Apr 8, 2024 at 1:59 PM Reinette Chatre
> <reinette.chatre@...el.com> wrote:
>> On 4/8/2024 12:05 PM, Peter Newman wrote:
>>> On Sun, Apr 7, 2024 at 12:21 PM Reinette Chatre
>>> <reinette.chatre@...el.com> wrote:

>>> wrappers for the mon and alloc enable keys[1], so I can only assume
>>> they are architecture-independent in concept.
>>
>> The wrappers are intended to be architecture-independent, but the keys
>> are architecture dependent. Quoting the commit you linked to:
>> "This means other architectures don't have to mirror the static keys"
> 
> The static keys seem to exist mainly for the benefit of
> __resctrl_sched_in(), so if it becomes architecture-agnostic, I think
> it would make sense for the static keys to move into the FS code with
> it. I don't see any other usage of these keys in the code that
> remained under arch/x86 on James' latest series.

Good point. James untangled the static keys from multiple usages with
only context switching remaining.
If its only use remains to avoid runtime checks in __resctrl_sched_in()
then it sounds reasonable that the static keys follow
__resctrl_sched_in() to FS code.

Reinette