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Date:   Mon, 12 Dec 2022 11:14:16 +0100
From:   Peter Zijlstra <peterz@infradead.org>
To:     Tejun Heo <tj@kernel.org>
Cc:     torvalds@linux-foundation.org, mingo@redhat.com,
        juri.lelli@redhat.com, vincent.guittot@linaro.org,
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Subject: Re: [PATCHSET RFC] sched: Implement BPF extensible scheduler class
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References: <20221130082313.3241517-1-tj@kernel.org>
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On Tue, Nov 29, 2022 at 10:22:42PM -1000, Tejun Heo wrote:

> Rolling out kernel upgrades is a slow and iterative process. At a large scale
> it can take months to roll a new kernel out to a fleet of servers. While this
> latency is expected and inevitable for normal kernel upgrades, it can become
> highly problematic when kernel changes are required to fix bugs. Livepatch [9]
> is available to quickly roll out critical security fixes to large fleets, but
> the scope of changes that can be applied with livepatching is fairly limited,
> and would likely not be usable for patching scheduling policies. With
> sched_ext, new scheduling policies can be rapidly rolled out to production
> environments.

I don't think we can or should use this argument to push BPF into ever
more places.