Public bug reported:
[Impact]
* The C library shipped in libc6 is built with GCC's default behavior of
omitting the frame pointer that makes tracing and profiling harder.
Building GLibc with -fno-omit-frame-pointer and shipping it in an
optional libc6-prof binary package would help tracing and profiling
efforts.
[Test Case]
* Install libc6-prof and start tracing in one shell:
sudo bpftrace -e 't:syscalls:sys_enter_clock_nanosleep /comm == "sleep"/
{printf("%s\n", ustack);}'
Attaching 1 probe...
clock_nanosleep+94
__nanosleep+23
0x5652a2e6b827
* Run the traced program in a different shell
env LD_LIBRARY_PATH=/lib/libc6-prof/x86_64-linux-gnu sleep 1
* Repeat it without using the libc6-prof library:
ubuntu@ff-glibc:~$ sleep 1
ubuntu@ff-glibc:~$ sudo bpftrace -e 't:syscalls:sys_enter_clock_nanosleep
/comm == "sleep"/ {printf("%s\n", ustack); }'
Attaching 1 probe...
clock_nanosleep+84
[ Where problems could occur ]
* Glibc does not build for some architectures with the additional
-fno-omit-frame-pointer option which is tracked in LP: #1898049.
* The -fno-omit-frame-pointer option may sneak in to the regular build, this is
convered in the test case.
* Libc6-prof may be slower thanks to the -fno-omit-frame-pointer option, this
is expected and this is the reason for shipping it in a separate package.
** Affects: glibc (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1908307
Title:
Please ship a glibc build for profiling in libc6-prof
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