Hi Hemant,
(2014/07/17 14:53), Hemant Kumar wrote:
This patchset helps in listing dtrace style markers(SDT) present in user spaceThanks for your work! This actually helps us a lot :)
applications through perf.
Notes/markers are placed at important places by the
developers. They have a negligible overhead when not enabled.
We can enable them and probe at these places and find some important information
like the arguments' values, etc.
We have lots of applications which use SDT markers today, like:At a glance, maybe we'd better have perf sdt-cache as like as perf buildid-cache
Postgresql, MySql, Mozilla, Perl, Python, Java, Ruby, libvirt, QEMU, glib
To add SDT markers into user applications:
We need to have this header sys/sdt.h present.
sys/sdt.h used is version 3.
If not present, install systemtap-sdt-devel package (for fedora-18).
Please refer to the Documentation patch to see how the SDT markers are added into
a program.
With this patchset,
- Use perf to list the markers in the app:
# perf list sdt ./user_app
./user_app :
%user_app:foo_start
%user_app:fun_start
- Also, we can see the SDT markers present in our system in the usual binaries.
These usual binaries are libraries (dsos) listed by ldconfig --print-cache and some
binaries present in PATH environment variable.
First, scan the binaries using :
# perf list sdt --scan
for manage sdt information. what would you think?
Creating a cache of SDT markers...Looks good :)
perf sdt cache created!
Use : "perf list sdt"
to see the SDT markers
After the sdt cache file is created, use perf list to view the markers :
# perf list sdt
%rtld : init_start
%rtld : init_complete
%rtld : map_failed
%rtld : map_start
%rtld : lll_futex_wake
...
...
%libgcc : unwind
%libvirt : rpc_server_client_auth_allow
%libvirt : rpc_server_client_auth_fail
%libvirt : rpc_server_client_auth_deny
It seems very useful for perf users.
Thank you,