systemtap probe at specific oracle function offset + BONUS

This is a trick i use to be able to put a systemtap probe at specific function offset in an oracle executable.That mean beside function entry and exit we can also probe at a specific offset such as “r0_aes_cbc_loop_dec_x86_intel+224”. Although this can be easily done using perf  (perf probe -oracle r0_aes_cbc_loop_dec_x86_intel+224)  or ftrace it seem not possible to do that using systemtap due to the lack of debuginfo .

This can be useful as a workaround for the error “registration error (rc 0)” described here or for other purpose !

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Enhancing DBMS_OUTPUT using systemtap

This is a short and quick note to show how we can enhance DBMS_OUTPUT capabilities using a small systemtap script without modifying the source code.Basically it will allow us to display the DBMS_OUTPUT message incrementally (the program don’t need to finish it’s execution) by attaching to an already running session (no need to enable DBMS_OUTPUT). The output can also be easily redirected to a file.

The idea is to try to access the function parameters.This can become complex in case of different arguments types and number but in our case there is only one argument of type varchar2.

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Geeky PL/SQL tracer/profiler : Another step

This is my second post under the theme of how to extend our capabilities to trace and profile PL/SQL code.This time motivated by a comment from Luca Canali on my previous post  :

So based on my previous work on geeky PL/SQL tracer let’s see how we can obtain a geeky PL/SQL on-CPU Flame Graph !

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Geeky PL/SQL tracer/profiler : First step

This blog post is about how to extend our capabilities to trace and profile PL/SQL code.It’s primarily motivated by few tweets from Franck Pachot and of course because it’s FUN !

Capture 02

Capture 01

So in the first part of this series we are going to answer to this questions : Can we map those underling function to the source PL/SQL object and line number ? Can we obtain a full trace ? Of course yes otherwise there will be no blog post :p

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