[Xen-devel] [RFC][PATCH] Hypervisor profiling using GCOV

[Tej <bewith.tej@xxxxxxxxx>]

gcov is a test coverage program. generally used with GCC to analyze
programs to help create more efficient, faster running code and to
discover untested parts of your program. Software developers also use
coverage testing in concert with testsuites,  to make sure software is
actually good enough for a release

Our efforts on the same line added the gcov(gcc) profiling support for
hypervisor only.
Current code base support xen-3.3.onwards, x86_32 and gcc 3.4 to 4.3.

xen-patch: code for hypervisor which populate the gcov_info (gcc 3.4
onward) with data file information, base code is taken from
http://ltp.sourceforge.net/coverage/gcov.php. added xen support and a
way to interact with linux since hypervisor itself cannot populate the
/proc filesystem.

linux-patch: code for linux kernel basically enquire the hypervisor
part to revert all data file information and populate the
/proc/xen/gcov with data and graph file (optional)

command-line/modules parameter:
1. xen-gcov-link: if set, it creates the *.c and *.gcno linking under
/proc/xen/gcov, else to run gcov/lcov we have to create manually
linking.
2. xen-gcov-update: update the data files after xen-gcov-update secs,
default value is 5sec... e.g while running a test suite, requires
lower value of xen-gcov-update.
   tunable xen-gcov-update exist at /proc/sys/xen
   usage: echo <num> >/proc/sys/xen/xen-gcov-update

Running lcov straight-a-way could be problematic because lcov is
written to see profiling info @/proc/gcov. To accomodate
/proc/xen/gcov edit the config file /etc/lcovrc parameter as
lcov_gcov_dir = /proc/gcov to /proc/xen/gcov and perform modprobe
xen-gcov-proc.
We are having patches to accomodate both but changing config file
could be a better options. Still if someone need patch please free to
mail me @bewith.tej@xxxxxxxxx

YES, We are aware that gcov profiling is quite basic profiling
concept, but its a begning from our end to make xen hypervisor best
and robust, in future we will be working on changes required for 64bit
hypervisor, older xen versions (if required), PERFMON features of
Modern CPU's.

Comments, reports, suggestions, and any other types of feedback is
more than welcome

        -tej & team

linux-2.6.18-gcov-v1.patch
Description: Text Data

xen-3.3.0-gcov-v1.patch
Description: Text Data

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel