LTTng bugs repository: Issueshttps://bugs.lttng.org/https://bugs.lttng.org/themes/lttng/favicon/a.ico?14249722912024-02-21T17:04:43ZLTTng bugs repository
Redmine Babeltrace - Feature #1410 (New): Add pretty-print sink options to override how to format floatin...https://bugs.lttng.org/issues/14102024-02-21T17:04:43ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Babeltrace 2, just like its predecessor babeltrace 1.5, uses "%g" to print floating point numbers.</p>
<p>It would be useful to let users optionally override the formatting for floating point numbers, perhaps with a pretty print sink option. They could then choose if exponent notation should be used or not, choose the precision, etc.</p> LTTng-tools - Bug #1379 (New): Document behavior of live mode with per-pid UST buffershttps://bugs.lttng.org/issues/13792023-06-01T18:48:58ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>There is a design limitation of per-pid UST buffers when used in live mode which should be documented.</p>
<p>Basically, because the per-pid buffers are reclaimed soon after the application exits, it may cause the events traced by a short-lived application to never appear in the output of a live trace when per-pid buffers are used.</p>
<p>This is caused by the fact that the live client periodically checks for new buffers, but there is no inherent reference kept on the streams before they disappear.</p>
<p>This means that the information will be available in the disk output of the trace, but it will be missing from the live mode output.</p>
<p>This could eventually be mitigated by keeping references to the streams received by the relay daemon which are of interest to a live client until they are referenced by the live client.</p> Babeltrace - Feature #1300 (New): babeltrace2 lacks knowledge of bitwise enum produced by lttng-m...https://bugs.lttng.org/issues/13002021-03-23T17:41:47ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>This is a follow up on <a class="external" href="https://review.lttng.org/c/babeltrace/+/3045">https://review.lttng.org/c/babeltrace/+/3045</a> now that end users are starting to contact us wondering why up-to-date lttng and babeltrace2 show incomplete information for bitwise enums.</p>
<p>I think we should implement a better stop-gap solution while awaiting CTF2. I recommend that we specialize the babeltrace2 CTF input plugin to detect traces produced by the lttng-modules kernel tracer, for specific known (hardcoded) events and fields which have a bitwise enum semantic, and use this hardcoded knowledge to print the correct bitwise enum to the end user rather than "<unknown>".</p>
<p>This should ensure the current producer/consumer tools work well together (show complete information about those bitwise enums) without requiring to modify tons of documentation about the specific flags needed for bt2 to handle lttng traces appropriately. And this would not lead to misleading scenarios where we print an unknown value as a bitwise enum by mistake.</p>
<p>Hardcoded producer detection/event/fields is of course a last resort solution awaiting proper self-description in the upcoming CTF2 spec.</p> LTTng - Feature #1288 (New): Combine all per-cpu shm areas for a channel into a single filehttps://bugs.lttng.org/issues/12882020-10-13T15:39:03ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>On the reason for having one shm file per cpu (per channel/per uid/per session): having one file per cpu is mainly done to facilitate NUMA-local memory allocation. That being said, I wonder if as a future improvement we could combine all per-cpu buffers into a single shm file, and issue numa_set_preferred piecewise when mmapping regions of the files. This would lessen the number of file descriptors needed by a significant amount. I suspect it would work, but we'd need to do some prototyping to validate this approach first.</p> LTTng-modules - Feature #1265 (New): Turn lttng-probes.c probe_list into a hash tablehttps://bugs.lttng.org/issues/12652020-05-06T17:14:59ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Turns O(n^2) trace systems registration (cost for n systems) into O(n). (O(1) per system)</p> LTTng-modules - Feature #1264 (New): NOHZ support for lib ring bufferhttps://bugs.lttng.org/issues/12642020-05-06T17:14:02ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>NOHZ infrastructure in the Linux kernel does not support notifiers chains, which does not let LTTng play nicely with low power consumption setups for flight recorder (overwrite mode) live traces. ne way to allow integration between NOHZ and LTTng would be to add support for such notifiers into NOHZ kernel infrastructure.</p> LTTng-modules - Feature #1263 (New): Re-integrate sample modules from libringbuffer into lttng-mo...https://bugs.lttng.org/issues/12632020-05-06T17:13:20ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Re-integrate sample modules from libringbuffer into lttng-modules. Those modules can be used as example of how to use libringbuffer in other contexts than LTTng, and are useful to perform benchmarks of the ringbuffer library. See: <a class="external" href="https://github.com/compudj/linux-libringbuffer/tree/tip-current-ringbuffer-0.240">https://github.com/compudj/linux-libringbuffer/tree/tip-current-ringbuffer-0.240</a></p> LTTng-tools - Bug #1256 (New): Check babeltrace1 stderr output in testshttps://bugs.lttng.org/issues/12562020-04-08T19:23:18ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Currently, babeltrace1 stderr's output contains warnings which are not checked by the tests. Those do not fail the overall babeltrace execution, but end up being unexpected regressions when they appear between releases.</p>
<p>We could modify all babeltrace invocations to add a helper which saves the stderr output, and check that it is empty after babeltrace has completed execution. If non-empty, a test error would be reported.</p> Babeltrace - Bug #1221 (New): Babeltrace 2 sometimes fail on live trace with lttng-clear featurehttps://bugs.lttng.org/issues/12212020-02-17T20:52:19ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Babeltrace 2 sometimes fail on live trace with lttng-clear feature</p>
<p>This may happen in a scenario where per-pid buffers are used, an application has just quit, and babeltrace 2 observes a stream in make_viewer_streams, but then fails to open the associated index or data file on the first get_next_index because it has been unlinked by clear.</p>
<p>The babeltrace output is:</p>
<pre>
12-04 14:01:48.455 11884 11884 E PLUGIN/CTF/MSG-ITER create_msg_stream_end@msg-iter.c:2464 [lttng-live] Cannot create stream for stream message: notit-addr=0x55b89f957980
12-04 14:01:48.455 11884 11884 W LIB/MSG-ITER bt_self_component_port_input_message_iterator_next@iterator.c:906 Component input port message iterator's "next" method failed: iter-addr=0x55b89f93f510, iter-upstream-comp-name="lttng-live", iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=SOURCE, iter-upstream-comp-class-name="lttng-live", iter-upstream-comp-class-partial-descr="Connect to an LTTng relay daemon", iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
12-04 14:01:48.455 11884 11884 E PLUGIN/FLT.UTILS.MUXER muxer_upstream_msg_iter_next@muxer.c:444 [muxer] Error or unsupported status code: status-code=-1
12-04 14:01:48.455 11884 11884 E PLUGIN/FLT.UTILS.MUXER validate_muxer_upstream_msg_iters@muxer.c:975 [muxer] Cannot validate muxer's upstream message iterator wrapper: muxer-msg-iter-addr=0x55b89f950950, muxer-upstream-msg-iter-wrap-addr=0x55b89f9415d0
12-04 14:01:48.455 11884 11884 E PLUGIN/FLT.UTILS.MUXER muxer_msg_iter_next@muxer.c:1371 [muxer] Cannot get next message: comp-addr=0x55b89f93ebc0, muxer-comp-addr=0x55b89f93ec40, muxer-msg-iter-addr=0x55b89f950950, msg-iter-addr=0x55b89f93f3a0, status=ERROR
12-04 14:01:48.455 11884 11884 W LIB/MSG-ITER bt_self_component_port_input_message_iterator_next@iterator.c:906 Component input port message iterator's "next" method failed: iter-addr=0x55b89f93f3a0, iter-upstream-comp-name="muxer", iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=FILTER, iter-upstream-comp-class-name="muxer", iter-upstream-comp-class-partial-descr="Sort messages from multiple inpu", iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
12-04 14:01:48.455 11884 11884 W LIB/GRAPH consume_graph_sink@graph.c:596 Component's "consume" method failed: status=ERROR, comp-addr=0x55b89f93ed30, comp-name="pretty", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="pretty", comp-class-partial-descr="Pretty-print messages (`text` fo", comp-class-is-frozen=0, comp-class-so-handle-addr=0x55b89f94c740, comp-class-so-handle-path="/usr/local/lib/babeltrace2/plugins/babeltrace-plugin-text.so", comp-input-port-count=1, comp-output-port-count=0
12-04 14:01:48.456 11884 11884 E CLI cmd_run@babeltrace2.c:2574 Graph failed to complete successfully
ERROR: [Babeltrace CLI] (babeltrace2.c:2574)
Graph failed to complete successfully
CAUSED BY [Babeltrace library] (graph.c:596)
Component's "consume" method failed: status=ERROR, comp-addr=0x55b89f93ed30,
comp-name="pretty", comp-log-level=WARNING, comp-class-type=SINK,
comp-class-name="pretty", comp-class-partial-descr="Pretty-print messages
(`text` fo", comp-class-is-frozen=0, comp-class-so-handle-addr=0x55b89f94c740,
comp-class-so-handle-path="/usr/local/lib/babeltrace2/plugins/babeltrace-plugin-text.so",
comp-input-port-count=1, comp-output-port-count=0
CAUSED BY [Babeltrace library] (iterator.c:906)
Component input port message iterator's "next" method failed:
iter-addr=0x55b89f93f3a0, iter-upstream-comp-name="muxer",
iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=FILTER,
iter-upstream-comp-class-name="muxer",
iter-upstream-comp-class-partial-descr="Sort messages from multiple inpu",
iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
CAUSED BY [Babeltrace library] (iterator.c:906)
Component input port message iterator's "next" method failed:
iter-addr=0x55b89f93f510, iter-upstream-comp-name="lttng-live",
iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=SOURCE,
iter-upstream-comp-class-name="lttng-live",
iter-upstream-comp-class-partial-descr="Connect to an LTTng relay daemon",
iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
</pre>
<p>notit->stream is expected not to be NULL when reaching the state STATE_EMIT_MSG_STREAM_END, but if no packet was received, it is indeed still NULL, because it is the packet header being read that moves to the STATE_CHECK_EMIT_MSG_STREAM_BEGINNING state (after_packet_context_state()).</p> LTTng - Bug #1192 (New): Web documentation improvement: describe use of CREATE_TRACE_POINTS for l...https://bugs.lttng.org/issues/11922019-08-05T14:36:42ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>Following discussion with David Goulet who is currently instrumenting the tor project with lttng-ust, it appears that the following use-case should be documented more clearly in the web documentation:</p>
<ul>
<li>Instrumentation of applications with LTTng-UST</li>
</ul>
<p>A tracepoint provider header should be included <em>once</em> per application within a compile unit after a #define CREATE_TRACE_POINTS.</p>
<p>It can be included multiple times throughout other compile units of the applications, but make sure the CREATE_TRACE_POINTS macro is not defined before those include, otherwise LTTng-UST will complain about multiple tracepoint probe definitions.</p> LTTng-modules - Feature #1061 (New): New btrfs events should be added to lttng-modules instrument...https://bugs.lttng.org/issues/10612016-08-30T21:23:10ZMathieu Desnoyersmathieu.desnoyers@efficios.comBabeltrace - Feature #1045 (New): Wire up debug info on lttng_ust_cyg_profile event fieldshttps://bugs.lttng.org/issues/10452016-07-13T14:53:52ZMathieu Desnoyersmathieu.desnoyers@efficios.com
<p>#lttng paste</p>
<p>09:56 < rnsanchez> is there a default procedure for "hydrating" instrument-functions traces like this?<br />09:56 < rnsanchez> [13:54:09.866652414] (+0.000001178) priminho lttng_ust_cyg_profile:func_exit: { cpu_id = 1 }, { addr = 0x46BB90, call_site = 0x46BF7B }<br />09:56 < rnsanchez> (kind of replacing the addr with their proper symbols)<br />09:57 < milian> rnsanchez: I'm not an lttng dev, but could imagine that one would be able to write that by analyzing mmap + openat to find the offset into a library, which you can then feed into addr2line, or libdw/libbacktrace<br />09:59 < rnsanchez> I could propably pass it (babeltrace) through some script to do that. but since the trace is huge (and this is not even a "real" trace), I was wondering if there is a better way to do that<br />09:59 < milian> I'd also be interested in that<br />10:00 < rnsanchez> well maybe there is one. building a symbol-table cache for the known things (a binary of special interest) and then feeding babeltrace through awk, replacing the symbols found with their names<br />10:01 < rnsanchez> some would miss, of course, but perhaps a good amount would help<br />10:46 < Compudj> rnsanchez, milian: currently, babeltrace is a bit "hardwired" to the "ip" context for symbol resolution<br />10:46 < Compudj> but all the infrastructure code is there<br />10:49 < Compudj> see babeltrace: formats/ctf-text/types/integer.c<br />10:49 < Compudj> there is a call to ctf_text_integer_write_debug_info<br />10:50 < Compudj> implemented in include/babeltrace/trace-debug-info.h<br />10:50 < Compudj> it checks if integer_definition->debug_info_src is non-null<br />10:51 < Compudj> this is wired up in lib/debug-info.c register_event_debug_infos()<br />10:51 < Compudj> it is where it is tied to the "ip" context<br />10:51 < Compudj> it should be extended to be tied to the lttng_ust_cyg_profile event fields too</p> LTTng-modules - Feature #964 (New): Implement support for persistent memory buffershttps://bugs.lttng.org/issues/9642015-10-22T20:41:43ZMathieu Desnoyersmathieu.desnoyers@efficios.comLTTng-modules - Feature #963 (New): Implement user-space stack dump contexthttps://bugs.lttng.org/issues/9632015-10-22T20:41:10ZMathieu Desnoyersmathieu.desnoyers@efficios.comLTTng-modules - Feature #962 (New): add x86 exceptions.h and irq_vectors.h instrumentation (and m...https://bugs.lttng.org/issues/9622015-10-22T19:47:19ZMathieu Desnoyersmathieu.desnoyers@efficios.com