linux-kernel - Re: [PATCH] Revert 9fc2105aeaaf56b0cf75296a84702d0f9e64437b to fix pyaudio (and probably more)

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Message-ID: <CA+55aFw8x01fBKczTSNkAZ06rwULVp0A=pASJACs8S1SB_Orew@mail.gmail.com>
Date:	Tue, 6 Jan 2015 17:20:06 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Pavel Machek <pavel@....cz>,
	Marc Zyngier <marc.zyngier@....com>,
	kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Revert 9fc2105aeaaf56b0cf75296a84702d0f9e64437b to fix
 pyaudio (and probably more)

On Tue, Jan 6, 2015 at 3:42 PM, Catalin Marinas <catalin.marinas@....com> wrote:
>>
>> That's what bogomips *is*, for chrissake! It's a bogus measure of how
>> many times you go through the delay loop.
>
> I think that's where the misunderstanding is. We don't have any idea
> how many times we go through the delay loop. We just go through the
> delay loop until the counter (driven by an independent frequency)
> changes X times.

.. and that's exactly what we do on x86 too with the TSC. It's fine.

> With the current arm timer-based (and arm64) implementation, the
> reported BogoMIPS has nothing to do with the CPU benchmark. It just
> tells you that a X MHz counter needs X*1000000/HZ ticks per jiffy.

Yes. And that's a valid bogomips. We've done that for ages on x86.

Really, the "problem" that people wonder why some bogomips value is
lower or higher isn't a problem. Just explain it to them. Or ignore
them when they ask.

Bogomips is a delay value for the micro-second delay loop. Nothing
less, nothing more.

                     Linus
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