linux-kernel - Re: [PATCH v9 04/10] x86: refcount: prevent gcc distortions

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Message-ID: <20181004090128.GA21864@gmail.com>
Date:   Thu, 4 Oct 2018 11:01:28 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Nadav Amit <namit@...are.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, Jan Beulich <JBeulich@...e.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v9 04/10] x86: refcount: prevent gcc distortions

* Nadav Amit <namit@...are.com> wrote:

> Finally, note that it’s not as if the binary always becomes smaller.
> Overall, with the full patch-set it is slightly bigger. But still, that’s
> how it was supposed to be if gcc wasn’t doing things badly.

So what I cited was the changelog for the refcount patch, which according to your
measurements reduced kernel image size.

For other patches where size grew I left that text intact.

And yes, in this particular case a slight increase in kernel size might actually be
beneficial, as we get a lot more straight-line execution in exchange. So this is
not a show-stopper property as long as the bloat isn't large.

Thanks,

	Ingo