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Date: Thu, 16 Oct 2025 09:42:27 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: "Chen, Yu C" <yu.c.chen@intel.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>, Ingo Molnar <mingo@redhat.com>,
	K Prateek Nayak <kprateek.nayak@amd.com>,
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	Tim Chen <tim.c.chen@intel.com>, linux-kernel@vger.kernel.org,
	Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [PATCH 04/19] sched/fair: Introduce a static key to enable cache
 aware only for multi LLCs
Message-ID: <20251016074227.GY3289052@noisy.programming.kicks-ass.net>
References: <cover.1760206683.git.tim.c.chen@linux.intel.com>
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In-Reply-To: <3d7b6b2c-7b48-4bd5-87bf-39f4c72fa741@intel.com>

On Thu, Oct 16, 2025 at 01:01:05AM +0800, Chen, Yu C wrote:

> Oh, do you mean only using sched_cache_allowed in sched_cache_enabled()?
> I misunderstood that Peter suggested introducing only one key. But I didn't
> quite catch up - do you mean we should monitor the switch of FEAT, modify
> sched_cache_allowed when needed, and that the OS only queries
> sched_cache_allowed
> at runtime?

Just don't use sched_feat(), add a debugfs file like numa_balancing and
then combine the userspace and topology information when setting the one
static_branch.