De : David Goulet [mailto:[email protected]]
>
> I just pushed a fix with the auto spawned session daemon but not related
> to your problem.
>
> Is it possible for you to test with the latest git head of lttng-tools
> because since the commit 9beed4c there is a large number of fixes!
>
> The session daemon sends a signal to the parent (here lttng client) when
> it is ready to process commands. So, the module are loaded for sure at
> this time.
>
> I'm unable to reproduce your problem... so what I can recommend is to
> report *any* compilation error with the latest git head you have and
> I'll see if it's related to your problem. You might want to check also
> if all lttng-modules are unloaded when NO session daemon is running (#
> lsmod | grep ltt).
>
> Also, with lttng-tools commit bcfa8a05018b339b9b5609fe975a3a7b29cc0c6e,
> using --help/-h with any lttng commands does NOT spawned the session
> daemon anymore.
>
> Please let me know if you are still having the problem with those
> recommendations.
Well, the good news is that the new head (lttng-tools-2.0-pre16+-76150f6
2012-01-18 17:21) compiles correctly (no warnings, no errors in bootstrap,
configure, make and install logs). The bad news is that it still misbehaves.
Here's my session log, edited for brevity:
$ sudo lttng list -k
Spawning a session daemon
Kernel events:
-------------
sched_kthread_stop (type: tracepoint)
sched_kthread_stop_ret (type: tracepoint)
[...]
kvm_ioapic_set_irq (type: tracepoint)
kvm_msi_set_irq (type: tracepoint)
(type: tracepoint) [disabled]
(type: tracepoint) [disabled]
[... 27 more instances ...]
(type: tracepoint) [disabled]
(type: tracepoint) [disabled]
$ sudo lttng list -k
Kernel events:
-------------
sched_kthread_stop (type: tracepoint)
sched_kthread_stop_ret (type: tracepoint)
[...]
kvm_ioapic_set_irq (type: tracepoint)
kvm_msi_set_irq (type: tracepoint)
kvm_ack_irq (type: tracepoint)
kvm_mmio (type: tracepoint)
[...]
block_bio_remap (type: tracepoint)
block_rq_remap (type: tracepoint)
When I kill the lttng-sessiond daemon, all 17 lttng-modules are unloaded.
I tried doing 'sudo modprobe lttng_probe_block' before calling 'sudo lttng
list -k' to see if that wouldn't un-anonymise the block_* tracepoints (which I
think are serviced by the lttng_probe_block module). The module loaded along
with a handful of other modules it depends on (ltt_relay, lttng_kretprobes,
lttng_kprobes, lttng_ftrace, lib_ring_buffer) but 'sudo lttng list -k' yielded
precisely the same output.
-----
I'd like to take this opportunity to point out a problem when running lttng
from an unelevated account:
$ lttng list -k
Spawning a session daemon
FATAL: Error inserting lttng_ftrace
(/lib/modules/2.6.38-020638-generic/extra/probes/lttng-ftrace.ko): Operation
not permitted
FATAL: Error inserting lttng_kprobes
(/lib/modules/2.6.38-020638-generic/extra/probes/lttng-kprobes.ko): Operation
not permitted
[... 14 more FATAL errors interleaved with 30 WARNINGs ...]
WARNING: Error inserting ltt_relay
(/lib/modules/2.6.38-020638-generic/extra/ltt-relay.ko): Operation not permitted
FATAL: Error inserting lttng_probe_sched
(/lib/modules/2.6.38-020638-generic/extra/probes/lttng-probe-sched.ko):
Operation not permitted
Error: Unable to list kernel events
Error: Kernel tracer not available
If the error is FATAL, why does lttng keep going? The final error message
could be improved to read something like "Error: Kernel tracer not available or
not accessible at your privilege level", in order to at least hint at what the
source of the problem is.
Daniel U. Thibault
R & D pour la défense Canada - Valcartier (RDDC Valcartier) / Defence R&D
Canada - Valcartier (DRDC Valcartier)
Système de systèmes (SdS) / System of Systems (SoS)
Solutions informatiques et expérimentations (SIE) / Computing Solutions and
Experimentations (CSE)
2459 Boul. Pie XI Nord
Québec, QC G3J 1X5
CANADA
Vox : (418) 844-4000 x4245
Fax : (418) 844-4538
NAC: 918V QSDJ
Gouvernement du Canada / Government of Canada
<http://www.valcartier.drdc-rddc.gc.ca/>
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