linux-kernel - Re: [PATCH v3 sched_ext/for-6.13] sched_ext: Do not enable LLC/NUMA optimizations when domains overlap

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Message-ID: <Zy1iUXxJE1qQLIsz@slm.duckdns.org>
Date: Thu, 7 Nov 2024 14:58:57 -1000
From: Tejun Heo <tj@...nel.org>
To: Andrea Righi <arighi@...dia.com>
Cc: David Vernet <void@...ifault.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 sched_ext/for-6.13] sched_ext: Do not enable LLC/NUMA
 optimizations when domains overlap

On Fri, Nov 08, 2024 at 01:01:36AM +0100, Andrea Righi wrote:
> When the LLC and NUMA domains fully overlap, enabling both optimizations
> in the built-in idle CPU selection policy is redundant, as it leads to
> searching for an idle CPU within the same domain twice.
> 
> Likewise, if all online CPUs are within a single LLC domain, LLC
> optimization is unnecessary.
> 
> Therefore, detect overlapping domains and enable topology optimizations
> only when necessary.
> 
> Moreover, rely on the online CPUs for this detection logic, instead of
> using the possible CPUs.
> 
> Fixes: 860a45219bce ("sched_ext: Introduce NUMA awareness to the default idle selection policy")
> Signed-off-by: Andrea Righi <arighi@...dia.com>

Applied to sched_ext/for-6.13.

Thanks.

-- 
tejun