From: Peter Zijlstra <peterz@infradead.org>
To: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Mark Wielaard <mjw@redhat.com>,
utrace-devel <utrace-devel@redhat.com>
Subject: Re: [RFC] [PATCH 4/7] Uprobes Implementation
Date: Fri, 15 Jan 2010 14:47:56 +0100 [thread overview]
Message-ID: <1263563276.4244.426.camel@laptop> (raw)
In-Reply-To: <20100115133825.GQ4822@redhat.com>
On Fri, 2010-01-15 at 08:38 -0500, Frank Ch. Eigler wrote:
> Hi -
>
> On Fri, Jan 15, 2010 at 02:25:30PM +0100, Peter Zijlstra wrote:
> > [...]
> > > utrace is not a form of punishment inflicted upon the undeserving. It
> > > is a service layer that uprobes et alii are built upon. You as a
> > > potential uprobes client need not also talk directly to it, if you
> > > wish to reimplement task-finder-like services some other way.
> >
> > [...]
> > But yes, I think that for most purposes utrace is a punishment, its way
> > too heavy, I mean, trap, generate a signal, catch the signal, that's
> > like an insane amount of code to jump through in order to get that trap.
>
> At the bottom, there will be an int3 in the userspace text page.
> There will be a trap taken, no matter what. Code must figure out
> whether this trap came from an in-kernel client such as uprobes, or
> whether it is to be passed through to a userspace debugger via ptrace
> (or the gdbstub). This part is unavoidable if you wish to be
> compatible.
Sure, a lookup against existing probe sites on trap is unavoidable, if
you find a match, you call a probe specific handler and deal with it
there, if you don't you'll eventually generate a SIGTRAP and fall back
to userspace.
Thing is, utrace doesn't do that (nor should it), its something the
uprobe interface should implement just like kprobes does.
> I'm not sure, but it sounds like the part you're complaining about is
> how utrace ultimately reports the trap to uprobes: i.e.,
> utrace_get_signal()? Is that the "insane amount of code"?
Well when tracing/profiling every instruction is too much. Having to
needlessly raise a signal only to catch it again a short bit later
sounds like obvious waste to me.
> > Furthermore it requires stopping and resuming tasks and nonsense like
> > that, that's unwanted in many cases, just run stuff from the trap site
> > and you're done.
>
> I don't know what you mean exactly. A trap already stopped task.
> utrace merely allows various clients to inspect/manipulate the state
> of the task at that moment. It does not add any context switches or
> spurious stop/resumue operations.
Srikar seemed to suggest it needed stop/resume.
next prev parent reply other threads:[~2010-01-15 13:48 UTC|newest]
Thread overview: 158+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-11 12:25 [RFC] [PATCH 0/7] UBP, XOL and Uprobes Srikar Dronamraju
2010-01-11 12:25 ` [RFC] [PATCH 1/7] User Space Breakpoint Assistance Layer (UBP) Srikar Dronamraju
2010-01-14 11:08 ` Peter Zijlstra
2010-01-14 19:46 ` Jim Keniston
2010-01-15 9:02 ` Peter Zijlstra
2010-01-15 21:07 ` Jim Keniston
2010-01-15 21:49 ` Peter Zijlstra
2010-01-16 0:58 ` Jim Keniston
2010-01-16 10:33 ` Peter Zijlstra
2010-01-17 0:12 ` Bryan Donlan
2010-01-18 7:37 ` Peter Zijlstra
2010-01-17 14:37 ` Avi Kivity
2010-01-15 9:03 ` Peter Zijlstra
2010-01-15 9:38 ` Ananth N Mavinakayanahalli
2010-01-15 9:50 ` Peter Zijlstra
2010-01-15 10:10 ` Ananth N Mavinakayanahalli
2010-01-15 10:13 ` Peter Zijlstra
2010-01-15 10:22 ` Ananth N Mavinakayanahalli
2010-01-15 10:56 ` Peter Zijlstra
2010-01-15 11:02 ` Peter Zijlstra
2010-01-15 21:19 ` Jim Keniston
2010-01-17 14:39 ` Avi Kivity
2010-01-17 14:52 ` Peter Zijlstra
2010-01-17 14:56 ` Avi Kivity
2010-01-17 15:01 ` Peter Zijlstra
2010-01-20 12:55 ` Pavel Machek
2010-01-17 14:59 ` Avi Kivity
2010-01-17 15:03 ` Peter Zijlstra
2010-01-17 19:33 ` Avi Kivity
2010-01-18 7:45 ` Peter Zijlstra
2010-01-18 11:01 ` Avi Kivity
2010-01-18 11:44 ` Peter Zijlstra
2010-01-18 12:01 ` Avi Kivity
2010-01-18 12:06 ` Peter Zijlstra
2010-01-18 12:09 ` Avi Kivity
2010-01-18 12:13 ` Pekka Enberg
2010-01-18 12:17 ` Avi Kivity
2010-01-18 12:24 ` Peter Zijlstra
2010-01-18 12:24 ` Pekka Enberg
2010-01-18 12:44 ` Srikar Dronamraju
2010-01-18 12:51 ` Pekka Enberg
2010-01-18 12:53 ` Avi Kivity
2010-01-18 12:57 ` Pekka Enberg
2010-01-18 13:06 ` Avi Kivity
2010-01-18 22:15 ` Jim Keniston
2010-01-19 8:07 ` Avi Kivity
2010-01-19 17:47 ` Jim Keniston
2010-01-19 18:06 ` Frederic Weisbecker
2010-01-20 6:36 ` Srikar Dronamraju
2010-01-20 10:51 ` Frederic Weisbecker
2010-01-20 19:31 ` Masami Hiramatsu
2010-01-20 9:43 ` Avi Kivity
2010-01-20 9:57 ` Peter Zijlstra
2010-01-20 12:22 ` Avi Kivity
2010-01-27 8:24 ` Ingo Molnar
2010-01-27 8:35 ` Avi Kivity
2010-01-27 9:08 ` Ingo Molnar
2010-01-27 9:25 ` Avi Kivity
2010-01-27 10:23 ` Ingo Molnar
2010-02-07 13:47 ` Avi Kivity
2010-01-20 10:45 ` Srikar Dronamraju
2010-01-20 12:23 ` Avi Kivity
2010-01-20 18:31 ` Andi Kleen
2010-01-20 19:34 ` Jim Keniston
2010-01-20 19:58 ` Andi Kleen
2010-01-20 20:28 ` Jim Keniston
2010-01-18 13:05 ` Peter Zijlstra
2010-01-18 13:34 ` Mark Wielaard
2010-01-18 19:49 ` Jim Keniston
2010-01-18 15:43 ` Ananth N Mavinakayanahalli
2010-01-18 16:52 ` Avi Kivity
2010-01-18 17:10 ` Ananth N Mavinakayanahalli
2010-01-18 12:14 ` Peter Zijlstra
2010-01-18 12:37 ` Avi Kivity
2010-01-18 13:15 ` Peter Zijlstra
2010-01-18 13:33 ` Avi Kivity
2010-01-18 13:34 ` K.Prasad
2010-01-20 15:57 ` Mel Gorman
2010-01-20 18:32 ` Andi Kleen
2010-01-18 11:45 ` Peter Zijlstra
2010-01-11 12:25 ` [RFC] [PATCH 2/7] x86 support for UBP Srikar Dronamraju
2010-01-11 12:25 ` [RFC] [PATCH 3/7] Execution out of line (XOL) Srikar Dronamraju
2010-01-14 11:08 ` Peter Zijlstra
2010-01-14 22:43 ` Jim Keniston
2010-01-15 9:07 ` Peter Zijlstra
2010-01-15 11:12 ` Srikar Dronamraju
2010-01-15 20:18 ` Jim Keniston
2010-01-11 12:25 ` [RFC] [PATCH 4/7] Uprobes Implementation Srikar Dronamraju
2010-01-12 2:01 ` Paul E. McKenney
2010-01-12 8:21 ` Srikar Dronamraju
2010-01-12 5:36 ` Frederic Weisbecker
2010-01-12 8:14 ` Ananth N Mavinakayanahalli
2010-01-13 0:53 ` Jim Keniston
2010-01-14 11:12 ` Peter Zijlstra
2010-01-12 8:54 ` Srikar Dronamraju
2010-01-14 11:09 ` Peter Zijlstra
2010-01-14 22:49 ` Jim Keniston
2010-01-15 9:10 ` Peter Zijlstra
2010-01-15 9:26 ` Frank Ch. Eigler
2010-01-15 9:35 ` Peter Zijlstra
2010-01-15 13:10 ` Frank Ch. Eigler
2010-01-15 13:25 ` Peter Zijlstra
2010-01-15 13:38 ` Frank Ch. Eigler
2010-01-15 13:47 ` Peter Zijlstra [this message]
2010-01-15 14:00 ` Frank Ch. Eigler
2010-01-15 14:06 ` Peter Zijlstra
2010-01-15 14:22 ` Frank Ch. Eigler
2010-01-15 14:40 ` Peter Zijlstra
2010-01-15 14:20 ` Srikar Dronamraju
2010-01-15 14:25 ` Peter Zijlstra
2010-01-15 23:11 ` Jim Keniston
2010-01-16 15:50 ` Frank Ch. Eigler
2010-01-15 10:26 ` Srikar Dronamraju
2010-01-15 10:33 ` Peter Zijlstra
2010-01-15 11:05 ` Maneesh Soni
2010-01-15 11:12 ` Peter Zijlstra
2010-01-15 11:18 ` Peter Zijlstra
2010-01-15 22:27 ` Jim Keniston
2010-01-15 23:44 ` Jim Keniston
2010-01-16 10:04 ` Peter Zijlstra
2010-01-15 13:08 ` Srikar Dronamraju
2010-01-15 13:16 ` Peter Zijlstra
2010-01-15 13:38 ` Peter Zijlstra
2010-01-11 12:25 ` [RFC] [PATCH 5/7] X86 Support for Uprobes Srikar Dronamraju
2010-01-14 11:13 ` Peter Zijlstra
2010-01-14 23:07 ` Jim Keniston
2010-01-11 12:26 ` [RFC] [PATCH 6/7] Uprobes Documentation Srikar Dronamraju
2010-01-11 12:26 ` [RFC] [PATCH 7/7] Ftrace plugin for Uprobes Srikar Dronamraju
2010-01-12 4:54 ` Frederic Weisbecker
2010-01-12 5:08 ` Steven Rostedt
2010-01-12 5:44 ` Frederic Weisbecker
2010-01-12 19:12 ` Tim Bird
2010-01-13 21:58 ` Masami Hiramatsu
2010-01-13 22:12 ` Masami Hiramatsu
2010-01-13 23:36 ` Steven Rostedt
2010-01-12 18:54 ` Frank Ch. Eigler
2010-01-12 22:00 ` Masami Hiramatsu
2010-01-12 22:15 ` Frank Ch. Eigler
2010-01-12 22:30 ` Masami Hiramatsu
2010-01-14 11:23 ` Peter Zijlstra
2010-01-14 11:29 ` Peter Zijlstra
2010-01-14 12:16 ` Mark Wielaard
2010-01-14 12:19 ` Peter Zijlstra
2010-01-14 11:35 ` Frederic Weisbecker
2010-01-14 11:43 ` Peter Zijlstra
2010-01-14 12:23 ` Frederic Weisbecker
2010-01-14 12:29 ` Peter Zijlstra
2010-01-18 13:00 ` Frederic Weisbecker
2010-01-11 14:35 ` [RFC] [PATCH 0/7] UBP, XOL and Uprobes Masami Hiramatsu
2010-01-11 22:59 ` Jim Keniston
2010-01-22 7:02 ` [RFC] [PATCH 0/7] UBP, XOL and Uprobes [ Summary of Comments and actions to be taken ] Srikar Dronamraju
2010-01-22 7:24 ` Ananth N Mavinakayanahalli
2010-01-22 10:47 ` Peter Zijlstra
2010-01-27 6:53 ` Peter Zijlstra
2010-01-27 8:24 ` Peter Zijlstra
2010-01-22 18:06 ` Peter Zijlstra
2010-01-22 18:36 ` Masami Hiramatsu
2010-01-22 23:55 ` Jim Keniston
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