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Feature #1180

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

Added by Naser Ez 11 months ago. Updated 11 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)

#1

Updated by Francis Deslauriers 11 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 11 months ago

  • Tracker changed from Bug to Feature

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