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Date:   Wed, 26 Jul 2023 11:17:52 +0200
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,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com,
        ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
        martin.lau@kernel.org, joshdon@google.com, brho@google.com,
        pjt@google.com, derkling@google.com, haoluo@google.com,
        dvernet@meta.com, dschatzberg@meta.com, dskarlat@cs.cmu.edu,
        riel@surriel.com, linux-kernel@vger.kernel.org,
        bpf@vger.kernel.org, kernel-team@meta.com,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCHSET v4] sched: Implement BPF extensible scheduler class
Message-ID: <20230726091752.GA3802077@hirez.programming.kicks-ass.net>
References: <20230711011412.100319-1-tj@kernel.org>
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On Fri, Jul 21, 2023 at 08:37:41AM -1000, Tejun Heo wrote:

> We are comfortable with the current API. Everything we tried fit pretty
> well. It will continue to evolve but sched_ext now seems mature enough for
> initial inclusion. I suppose lack of response doesn't indicate tacit
> agreement from everyone, so what are you guys all thinking?

I'm still hating the whole thing with a passion.

As can be seen from the wide-spread SCHED_DEBUG abuse; people are, in
general, not interested in doing the right thing. They prod random
numbers (as in really, some are just completely insane) until their
workload improves and call it a day.

There is not a single doubt in my mind that if I were to merge this,
there will be Enterprise software out there that will mandate its own
BPF sched thing, or else it won't work.

They will not care, they will not contribute, they might even pull a
RedHat and only share the code to customers.

We all loose in that scenario. Not least me, because I get the
additional maintenance burden.

I also don't see upsides to merging this. You all can play with
schedulers out-of-tree just fine and then submit what actually works.

So, since you wanted it in writing, here goes:

NAK