Please read my previous message once more:
Hi, I think you need to rebuild the test with '-g' switch.
If the test binary does not have debuginfo, opreport cannot
resolve that.
On Fri, 24 Mar 2017, dhara buch wrote:
Hi,
Yes, when I try to execute 'opreport --symbols --debug-info' command after doing profiling for a .c file (let operf ./test),
I am expecting 'test.c:line_no' in linear info field as you are getting 'exact_counts.c:13' in the following:
samples % linenr info image name symbol name
10 66.6667 (no location information) no-vmlinux /no-vmlinux
2 13.3333 exact_counts.c:13 exact_counts main
1 6.6667 exact_counts.c:10 exact_counts f_65535x
1 6.6667 exact_counts.c:9 exact_counts f_997x
1 6.6667 (no location information) ld-2.17.so _dl_fini
I tried to install debuginfo using
#debuginfo-install kernel command.
But when I execute 'opreport --symbols --debug-info', I get only (no location information) in all of my samples.
What may be the reason?
The reason is that OProfile cannot find debuginfo of your test app.
Probably because it does not contain any ;-)
Recompile your test application with the '-g' gcc switch.
FURTHER INFO:
If you are profiling an application installed from packages, you
need to have the corresponding debuginfo package. For example,
for profiling firefox, you need firefox-debuginfo (RHEL, Fedora,
CentOS) or (probably) firefox-dbg packages (Ubuntu). It's also
good to have the debuginfos of all the required libraries.
On RHEL/CentOS/Fedora, you can install that easily by:
debuginfo-install <your_package>
Cheers,
Michael
On Thu, Mar 23, 2017 at 8:08 PM, Michael Petlan <mpetlan@redhat.com> wrote:
On Thu, 23 Mar 2017, dhara buch wrote:
Hello,
I am doing profiling with command,
operf ./test --events=BR_INST_RETIRED
where test.c is a simple c language file.
then, I am trying to collect information with command
opreport --symbols --debug-info
From the documents of Oprofile, I assume that the above command lists profiling result as per the symbols i.e. I can get result showing samples, linear info, image
name and symbol name.
As per my command I expect my file name (test.c) to be in the linear info and image name, but shows [no location information] in linear info. The filename does not
get listed in image
name also.
What is lacking?
Hi, I think you need to rebuild the test with '-g' switch.
If the test binary does not have debuginfo, opreport cannot
resolve that.
Me trying with debuginfo:
samples % linenr info image name symbol name
10 66.6667 (no location information) no-vmlinux /no-vmlinux
2 13.3333 exact_counts.c:13 exact_counts main
1 6.6667 exact_counts.c:10 exact_counts f_65535x
1 6.6667 exact_counts.c:9 exact_counts f_997x
1 6.6667 (no location information) ld-2.17.so _dl_fini
And without:
samples % linenr info image name symbol name
10 55.5556 (no location information) no-vmlinux /no-vmlinux
3 16.6667 (no location information) exact_counts f_65535x
2 11.1111 (no location information) exact_counts main
1 5.5556 (no location information) ld-2.17.so _dl_add_to_slotinfo
1 5.5556 (no location information) ld-2.17.so _dl_next_tls_modid
1 5.5556 (no location information) ld-2.17.so _dl_relocate_object
Is this the problem you are asking about?
I tried to set vmlinux with operf --vmlinux option also where vmlinux file in in /usr/lib/debug/lib/4*/vmlinux, still the above commands do not list test file
entries.
The "--vmlinux" option is there for enabling this for samples
obtained in kernelspace.
By default (assuming you have no kernel debuginfo available),
operf marks all the samples taken in kernel (e.g. your program
called a syscall and the sample was taken when the syscall was
being executed or you profile systemwide) as "no-vmlinux".
This is sufficient if you care about userspace only and not about
the "time" spent in kernel.
If you care about kernelspace, you need the '--vmlinux' option
with correct path specified.
What is lacking?
Thank you,
Dhara buch
Has this helped?
Cheers,
Michael