Date: Wed, 2 May 2007 16:21:35 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Christoph Hellwig <hch@infradead.org>, Andi Kleen <andi@firstfloor.org>,
       linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, wfg@ustc.edu
Subject: Re: 2.6.22 -mm merge plans
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On Wed, 2 May 2007 19:11:04 -0400
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> > I didn't know that this was the plan.
> > 
> > The problem I have with this is that once we've merged one part, we're
> > committed to merging the other parts even though we haven't seen them yet.
> > 
> > What happens if there's a revolt over the next set of patches?  Do we
> > remove the core markers patches again?  We end up in a cant-go-forward,
> > cant-go-backward situation.
> > 
> > I thought the existing code was useful as-is for several projects, without
> > requiring additional patching to core kernel.  If such additional patching
> > _is_ needed to make the markers code useful then I agree that we should
> > continue to buffer the markers code in -mm until the
> > use-markers-for-something patches have been eyeballed.
> > 
> 
> My statement was probably not clear enough. The actual marker code is
> useful as-is without any further kernel patching required : SystemTAP is
> an example where they use external modules to load probes that can
> connect either to markers or through kprobes. LTTng, in its current state,
> has a mostly modular core that also uses the markers.

OK, that's what I thought.

> Although some, like Christoph and myself, think that it would benefit to
> the kernel community to have a common infrastructure for more than just
> markers (meaning common serialization and buffering mechanism), it does
> not change the fact that the markers, being in mainline, are usable by
> projects through additional kernel modules.
> 
> If we are looking at current "potential users" that are already in
> mainline, we could change blktrace to make it use the markers.

That'd be a useful demonstration.
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