linux-kernel - Re: [PATCH 1/2] x86/nmi: Optimize the check for being in the repeat

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Message-ID: <CALCETrUBebEndF1PJ9+6fdYVik9LC717JfEaNks9hXr-mzOF=A@mail.gmail.com>
Date:   Fri, 10 Mar 2017 11:03:46 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] x86/nmi: Optimize the check for being in the
 repeat_nmi code

On Fri, Mar 10, 2017 at 11:00 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Thu, Mar 9, 2017 at 11:20 PM, Ingo Molnar <mingo@...nel.org> wrote:
>>
>> Joking aside, I'll bite: while in the kernel we try to avoid ever actually
>> _writing_ new assembly code
>
> .. also, when we do, I think we should care about it.
>
> If you write asm, and the end result is noticeably worse than what
> your average compiler would generate, exactly why are you writing it
> in asm in the first place?
>
> So I think people should aim to avoid asm. Andy certainly knows that,
> and I loved his "rewrite a lot of the low-level system call code"
> patches.
>
> But the corollary to that is that if you _do_ write assembler, please
> have some pride in the code, and don't half-arse it.
>

Geez, I didn't expect anyone to take my silly comment remotely
seriously :)  And I do like Steven's patches.

--Andy, who just looked at binutils source to figure out WTF "nobits"
meant.  Take that, asm!