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From: Ingo Molnar <mingo@kernel.org>
To: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v2 0/8] scheduler tinification
Date: Tue, 13 Jun 2017 09:12:28 +0200	[thread overview]
Message-ID: <20170613071228.aw4z2xra37bci7ua@gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.20.1706111126300.29475@knanqh.ubzr>


* Nicolas Pitre <nicolas.pitre@linaro.org> wrote:

> > A series that shrinks the .text size of the allnoconfig core Linux kernel from 1MB 
> > to 9.9MB in isolation is not proof.
> 
> I assume you meant 0.9MB.

0.992 MB actually if we apply the ~8k .text savings. 0.9MB would imply 100k of 
savings on an allnoconfig kernel.

> It is no proof of course. But I'm following the well known and proven 
> "release early, release often" mantra here... unless this is no longer 
> promoted?

I'm following that same pattern: I gave you negative review feedback as early as 
possible. Fragmention of the scheduler ABI increases complexity and has knock-on 
costs - and the kernel size reduction for the usecase you cited are still 1-2 
orders of magnitude away from making a practical difference.

> > There will literally have to be two orders of magnitude more patches than that 
> > to reach the 32K size envelope, if I (very) optimistically assume that the 
> > difficulty to shrink code is constant (which it most certainly is not).
> 
> Once again, my goal is _not_ 32KB.
> 
> And I don't intend to shrink code. Most of the time I just want to 
> _remove_ code. Compiling it out to be precise. The goal of this series 
> is all about compiling out code. And to achieve that with the scheduler, 
> I simply moved some code to different source files and not including 
> those source files in the final build. That keeps the number of #ifdef's 
> to a minimum but it makes a big diffstat due to the code movement.

So I'm fine with most of the code movement - let's try this series without any of 
the more controversial bits which should make future arguments easier.

Thanks,

	Ingo

  reply	other threads:[~2017-06-13  7:12 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-06 23:24 Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 1/8] cpuset/sched: cpuset makes sense for SMP only Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 2/8] sched: omit stop_sched_class when !SMP Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 3/8] futex: make PI support optional Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 4/8] sched/deadline: move dl related code out of sched/core.c Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 5/8] sched/rt: move rt " Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 6/8] sched/deadline: make it configurable Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 7/8] rtmutex: compatibility wrappers when no RT support is configured Nicolas Pitre
2017-06-06 23:24 ` [PATCH v2 8/8] sched/rt: make it configurable Nicolas Pitre
2017-06-07 16:00 ` [PATCH v2 0/8] scheduler tinification Ingo Molnar
2017-06-07 17:09   ` Nicolas Pitre
2017-06-07 18:49     ` Alan Cox
2017-06-07 21:15       ` Nicolas Pitre
2017-06-07 21:53         ` Alan Cox
2017-06-08  7:59     ` Ingo Molnar
2017-06-08 18:14       ` Alan Cox
2017-06-08 20:16       ` Nicolas Pitre
2017-06-11  9:23         ` Ingo Molnar
2017-06-11 15:26           ` Nicolas Pitre
2017-06-11  9:42         ` Ingo Molnar
2017-06-11 16:45           ` Nicolas Pitre
2017-06-13  7:12             ` Ingo Molnar [this message]
2017-06-13 12:29               ` Nicolas Pitre

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