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Feature #1180

SDT tracing does not work when the probes are compiled with semaphores

Added by Naser Ez 8 months ago. Updated 8 months ago.

Status:
New
Priority:
Normal
Target version:
Start date:
03/27/2019
Due date:
% Done:

0%

Estimated time:

Description

Tracing SDT probes does not work when the probes are compiled with semaphores.

For example, when we have a probe like:

    Provider: nginx
    Name: http__subrequest__start
    Location: 0x0000000000429e9c, Base: 0x0000000000473810, Semaphore: 0x00000000006920ba

    Arguments: 8@%rbx__

then running the following command:

    lttng enable-event -k nginx:http__subrequest__start --userspace-probe=sdt:/usr/local/nginx/sbin/nginx:nginx:http__subrequest__start

will generate this error:

     Error: Event nginx:http__subrequest__start: Invalid userspace probe location (channel channel0, session auto-20190327-105118)

History

#1

Updated by Francis Deslauriers 8 months ago

As discussed on IRC, supporting probe points with semaphores would require significant engineering efforts. But we could improve the explanation printed by the error message.

#2

Updated by Francis Deslauriers 8 months ago

  • Tracker changed from Bug to Feature

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