Date:	Mon, 05 May 2008 11:58:57 -0700
From:	Daniel Walker <dwalker@...sta.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Sven-Thorsten Dietrich <sven@...bigcorporation.com>,
	Remy Bohmer <linux@...mer.net>,
	LKML <linux-kernel@...r.kernel.org>,
	RT <linux-rt-users@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jon Masters <jonathan@...masters.org>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: Preempt-RT patch for 2.6.25


On Mon, 2008-05-05 at 14:32 -0400, Steven Rostedt wrote:
> On Mon, 5 May 2008, Daniel Walker wrote:
> 
> >
> > That's really the point, you should have started with my version. I
> > released my changes long before the 2.6.25 release.
> 
> Sorry Daniel but you never proved to me that your version didn't break
> anything.  I'm not about to start with something that throws out all the
> archs, espically when Thomas has a port of another arch ready for me.
> 

No one can prove that code has no bugs.. It's not possible. Yes, my code
_might_ have a defect. Your going to have to come to terms with that if
you use my changes.

Dropping the architectures is something you will need to do anyway for
mainline integration. You'll have to do it for re-writes, and you'll
have to do it for bisection .. Ultimately it a good thing. Additionally
if you drop the architectures now you force people to test and re-port
which mean the port are more likely to work. Right now you really have
no idea of the condition of those ports.

> > > > Bisection is also required for mainline integration ..
> > >
> > > Bisection is required for each element, we don't need it for the entire
> > > tree (atm). If we waste our time making the entire tree fully bisectable,
> > > then it will be a lot of work to maintain that bisectability when we
> > > rewrite entire sections.
> >
> > Bisection is required for everything, every patch. I am giving you a
> > bisect tree, there is no time wasted (only mine)..
> 
> But you still need to show that it didn't brake anything, which you have
> not.

Your right I haven't , like I said no code is guaranteed bug free. Not
even your code.

> >
> > I'm not following your logic Steven .. You want bisection , that means
> > you should want to maintain it, and write code in the future which also
> > bisects.
> 
> I'll admit I would like a bisectable tree, and patches that are submitted
> are bisectable. But the patches are also moved around a bit to get
> the queue ready for mainline. That moving itself can break the
> bisectability of later patches.

It shouldn't .. If something did break you would need to move another
patch forward to correct it. I would imagine you would want all the
patches related to anything you push forward.

> >
> > If someone submits code which doesn't bisect you kick it the same way
> > it's kicked from mainline. That means future patches in -rt are ready
> > for mainline which helps further the goal of mainline integration.
> 
> Patches that come in now are usually simple fixes. Major developments are
> bisectable.

Then there shouldn't be any problems.

> >
> > > I am making it boot with certain parts intergrated. But my goal is not to
> > > have every single patch compile and boot. We'll worry about that when we
> > > need to push a part of the code in. But reality, what is there now, I can
> > > guarantee will not be the code that is pushed when it is ready.
> >
> > What you guarantee to happen in the future is irrelevant .. We want
> > bisection _now_ , not months from now..
> 
> Fine, produce your own tree, I'll produce mine.

I have my own tree already. Are you obsoleting your tree now?

> >
> > Bisection has lots of benefits, it's not just that one stupid
> > requirement mainline has and no one really cares about.
> 
> There is some benefits, but one thing you forget about the -rt patch, is
> that there's lots of variables.  A lot of bugs that I found in -rt is not
> about a bad patch, but usually because of the way rt works (preemptible
> spinlocks and interrupts as threads) that cause breakage, and a lot of
> that breakage is from a change in upstream, not the patch series. Having
> it bisectable doesn't always help.

Sure not everything can be bisected, but we don't currently have a
choice to bisect or not too .. Users are left to report the bug and hope
the right person sees it.

Daniel

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