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Message-ID: <20100129095152.GA360@elte.hu>
Date: Fri, 29 Jan 2010 10:51:52 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Ananth N Mavinakayanahalli <ananth@...ibm.com>
Cc: Jim Keniston <jkenisto@...ibm.com>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Kyle Moffett <kyle@...fetthome.net>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Fr??d??ric Weisbecker <fweisbec@...il.com>,
Oleg Nesterov <oleg@...hat.com>,
Steven Rostedt <rostedt@...dmis.org>,
LKML <linux-kernel@...r.kernel.org>,
Tom Tromey <tromey@...hat.com>,
"Frank Ch. Eigler" <fche@...hat.com>, linux-next@...r.kernel.org,
"H. Peter Anvin" <hpa@...or.com>, utrace-devel@...hat.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
Thomas Gleixner <tglx@...utronix.de>
Subject: Re: linux-next: add utrace tree
* Ananth N Mavinakayanahalli <ananth@...ibm.com> wrote:
> On Fri, Jan 29, 2010 at 10:11:16AM +0100, Ingo Molnar wrote:
> >
> > * Ananth N Mavinakayanahalli <ananth@...ibm.com> wrote:
> >
> > > On Fri, Jan 29, 2010 at 08:39:07AM +0100, Ingo Molnar wrote:
> > >
> > > ...
> > >
> > > > When we merged kprobes ~10 years ago we made the (rather bad) mistake of
> > > > merging a raw, opaque facility and leaving 'the rest' up to some other entity.
> > > > IBM kprobes hackers vanished the day the original kprobes code went upstream
> > > > and the high level entity never truly materialized in-kernel, for nearly a
> > > > decade!
> > >
> > > I don't know what you are referring to here... Kprobes was merged in 2.6.9
> > > (~August 2004 -- less than 6 years ago). [...]
> >
> > Ok, 6 years then :-)
> >
> > > [...] Since then, we did work on ports to powerpc and s390. We implemented
> > > kretprobes. We made it much scalable using RCU; we did the powerpc booster
> > > to skip single-step when possible, not to mention various bug fixes over the
> > > years.
> >
> > Except it had no real in-kernel user.
>
> Not that I want to rebut you Ingo, but there were in-kernel users since 2006
> (net/ipv4/tcp_probe.c) :-)
i said 'real' users. That usage in tcp_probe.c was (and is) really minimal and
never expanded really.
> Aside, I am also glad that we have more flexibility with the perf
> integration.
ok, good :)
Ingo
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