Chapter 24. Creating uprobes with perf
24.1. Creating uprobes at the function level with perf Copy linkLink copied to clipboard!
You can use the perf
tool to create dynamic tracepoints at arbitrary points in a process or application. These tracepoints can then be used in conjunction with other perf
tools such as perf stat
and perf record
to better understand the process or applications behavior.
Prerequisites
-
You have the
perf
user space tool installed as described in Installing perf.
Procedure
Create the uprobe in the process or application you are interested in monitoring at a location of interest within the process or application:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
24.2. Creating uprobes on lines within a function with perf Copy linkLink copied to clipboard!
These tracepoints can then be used in conjunction with other perf
tools such as perf stat
and perf record
to better understand the process or applications behavior.
Prerequisites
-
You have the
perf
user space tool installed as described in Installing perf. You have gotten the debugging symbols for your executable:
objdump -t ./your_executable | head
# objdump -t ./your_executable | head
Copy to Clipboard Copied! Toggle word wrap Toggle overflow NoteTo do this, the
debuginfo
package of the executable must be installed or, if the executable is a locally developed application, the application must be compiled with debugging information, the-g
option in GCC.
Procedure
View the function lines where you can place a uprobe:
perf probe -x ./your_executable -L main
$ perf probe -x ./your_executable -L main
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Output of this command looks similar to:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow Create the uprobe for the desired function line:
Copy to Clipboard Copied! Toggle word wrap Toggle overflow
24.3. Perf script output of data recorded over uprobes Copy linkLink copied to clipboard!
A common method to analyze data collected using uprobes is using the perf script
command to read a perf.data
file and display a detailed trace of the recorded workload.
In the perf script example output:
- A uprobe is added to the function isprime() in a program called my_prog
- a is a function argument added to the uprobe. Alternatively, a could be an arbitrary variable visible in the code scope of where you add your uprobe: