Bug #349


Filters don't work with apps compiled with old versions of LTTng

Added by Jesus Garcia almost 12 years ago. Updated almost 12 years ago.

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When filters are used on apps compiled with older versions of LTTng, the filters do not take effect and nothing is filtered out.
So there seems to be a backwards-compatibility issue.

To reproduce the fault apps were compiled with the following LTTng versions:
CURRENT HEAD: foss/babeltrace 2ae35d4 (HEAD, tag: v1.0.0-rc4) Update version to 1.0.0-rc4
CURRENT HEAD: foss/lttng-tools 6c12303 (HEAD, tag: v2.0.4) Update version to 2.0.4 stable
CURRENT HEAD: foss/lttng-ust f8b9341 (HEAD, tag: v2.0.4) Update version to 2.0.4
CURRENT HEAD: foss/userspace-rcu 3227f2c (HEAD, tag: v0.7.3) Update version to 0.7.3

For comparison, a session was executed using apps compiled with a recently installed version of LTTng (in this case the filters do work):
CURRENT HEAD: foss/babeltrace 9b3c1d6 (HEAD, origin/master, origin/HEAD) Fix: emf uri: surround by " "
CURRENT HEAD: foss/lttng-tools 6b8f2e6 (HEAD, origin/master, origin/HEAD) Add consumer commands to lttng.1 man page
CURRENT HEAD: foss/lttng-ust 82513db (HEAD, origin/master, origin/HEAD) Filter error message cleanup
CURRENT HEAD: foss/userspace-rcu a5a9f42 (HEAD, origin/master, origin/HEAD, master) Ensure that read-side functions meet 10-line LGPL criterion

Please see the attached log for details.


filters_dont_work_with_old_apps.txt (15.7 KB) filters_dont_work_with_old_apps.txt Jesus Garcia, 09/21/2012 10:21 AM
Actions #1

Updated by Mathieu Desnoyers almost 12 years ago

  • Status changed from New to Resolved
  • Assignee set to Mathieu Desnoyers

Applications compiled against lttng-ust 2.0 were compiled against a UST that did not support filtering. Therefore, the filtering feature is not available for those applications (unless they are recompiled against lttng-ust 2.1). Therefore, the expected behavior is that they behave like the 2.0 UST, which means that no filter is applied.

This is therefore not a regression, this is a known limitation of lttng-ust 2.0: the filtering feature was not there.

Short answer: if you want filtering in your applications, you will need to recompile the tracepoint probes against lttng-ust 2.1.



Actions #2

Updated by Anonymous almost 12 years ago

  • Status changed from Resolved to Invalid

Just to be pedantic, since nothing was done for this, it should be marked "invalid" since it's not actually a bug.


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