linux-kernel - Re: [rfc][patch 3/3] x86: optimise barriers

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Message-ID: <20071015115359.GB3015@ff.dom.local>
Date:	Mon, 15 Oct 2007 13:53:59 +0200
From:	Jarek Poplawski <jarkao2@...pl>
To:	Helge Hafting <helge.hafting@...el.hist.no>
Cc:	Nick Piggin <npiggin@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <ak@...e.de>
Subject: Re: [rfc][patch 3/3] x86: optimise barriers

On Mon, Oct 15, 2007 at 12:17:40PM +0200, Helge Hafting wrote:
> Jarek Poplawski wrote:
> >On Fri, Oct 12, 2007 at 02:44:51PM +0200, Helge Hafting wrote:
> >...
> >  
> >>The point is that we _trust_ intel when they says "this will work".
> >>Therefore, we can use the optimizations. It was never about
> >>legal matters. If we didn't trust intel, then we couldn't
> >>use their processors at all.
> >>    
> >
> >But there was nothing about trust. Usually you don't trust somebody
> >but somebody's opinions. The problem is there was no valid opinion,
> >or this opinion has been changed now (no reason to not trust yet...).
> >  
> "Trusting people or their opinions" is only about use of the
> english language, and not that intersting to bring up here.
> Surely you know that lots of people here have english as
> a secondary language only. Intersting for me to know, but
> probably not for everybody else.

Of curse, I know this problem: sometimes it's very hard to make people
believe it's my secondary language! But this time I didn't see any
language problem. I simply poined out that sometimes trusting could be
not enough - not necessarily in this case.

> >>We couldn't take the chance before. It was not documented
> >>to work, verification by testing would not be trivial at all for
> >>this case.
> >>Linux is about "stability first, then performance".
> >>Now we _know_ that we can have this optimization without
> >>compromising stability. Nobody knew before!
> >>    
> >
> >So, you think this would be the first or the least credibly
> >verified undocumented feature used in linux? Then, it seems
> >I can try to install this linux on my laptop at last! (...
> >And, I can trust you, it will not break anything...?)
> >  
> I never claimed that linux will work on your laptop, so no:
> You can't take my word for that, because I never gave it!
> It is well known that some laptops don't work with linux,
> I have no idea if yours will work, I don't even know what kind it is.

OK, this was supposed to be a joke... (Btw, can you remember burning
linux laptops?) I thought this "stability first" a bit funny, but this
was a really bad joke, sorry.

Thanks for these additional explanations - you are completely right!

Regards,
Jarek P.
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