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authorPeter Oberparleiter <oberpar@linux.vnet.ibm.com>2009-06-17 16:28:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-18 13:03:57 -0700
commit2521f2c228ad750701ba4702484e31d876dbc386 (patch)
tree2221de3e3de9512979b8244c6304366e3be5be63 /kernel/gcov/Kconfig
parent0b923606e75f1ab672e25b14ac039a1cdcfa382f (diff)
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gcov: add gcov profiling infrastructure
Enable the use of GCC's coverage testing tool gcov [1] with the Linux kernel. gcov may be useful for: * debugging (has this code been reached at all?) * test improvement (how do I change my test to cover these lines?) * minimizing kernel configurations (do I need this option if the associated code is never run?) The profiling patch incorporates the following changes: * change kbuild to include profiling flags * provide functions needed by profiling code * present profiling data as files in debugfs Note that on some architectures, enabling gcc's profiling option "-fprofile-arcs" for the entire kernel may trigger compile/link/ run-time problems, some of which are caused by toolchain bugs and others which require adjustment of architecture code. For this reason profiling the entire kernel is initially restricted to those architectures for which it is known to work without changes. This restriction can be lifted once an architecture has been tested and found compatible with gcc's profiling. Profiling of single files or directories is still available on all platforms (see config help text). [1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.html Signed-off-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Huang Ying <ying.huang@intel.com> Cc: Li Wei <W.Li@Sun.COM> Cc: Michael Ellerman <michaele@au1.ibm.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com> Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: WANG Cong <xiyou.wangcong@gmail.com> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Jeff Dike <jdike@addtoit.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/gcov/Kconfig')
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diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig
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+menu "GCOV-based kernel profiling"
+
+config GCOV_KERNEL
+ bool "Enable gcov-based kernel profiling"
+ depends on DEBUG_FS && CONSTRUCTORS
+ default n
+ ---help---
+ This option enables gcov-based code profiling (e.g. for code coverage
+ measurements).
+
+ If unsure, say N.
+
+ Additionally specify CONFIG_GCOV_PROFILE_ALL=y to get profiling data
+ for the entire kernel. To enable profiling for specific files or
+ directories, add a line similar to the following to the respective
+ Makefile:
+
+ For a single file (e.g. main.o):
+ GCOV_PROFILE_main.o := y
+
+ For all files in one directory:
+ GCOV_PROFILE := y
+
+ To exclude files from being profiled even when CONFIG_GCOV_PROFILE_ALL
+ is specified, use:
+
+ GCOV_PROFILE_main.o := n
+ and:
+ GCOV_PROFILE := n
+
+ Note that the debugfs filesystem has to be mounted to access
+ profiling data.
+
+config GCOV_PROFILE_ALL
+ bool "Profile entire Kernel"
+ depends on GCOV_KERNEL
+ depends on S390 || X86_32
+ default n
+ ---help---
+ This options activates profiling for the entire kernel.
+
+ If unsure, say N.
+
+ Note that a kernel compiled with profiling flags will be significantly
+ larger and run slower. Also be sure to exclude files from profiling
+ which are not linked to the kernel image to prevent linker errors.
+
+endmenu