[POWERPC] powerpc: Instrument Hypervisor Calls

Add instrumentation for hypervisor calls on pseries.  Call statistics
include number of calls, wall time and cpu cycles (if available) and
are made available via debugfs.  Instrumentation code is behind the
HCALL_STATS config option and has no impact if not enabled.

Signed-off-by: Mike Kravetz <kravetz@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index e29ef77d3b00..d7b2aedd89aa 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -18,6 +18,20 @@ config DEBUG_STACK_USAGE
 
           This option will slow down process creation somewhat.
 
+config HCALL_STATS
+        bool "Hypervisor call instrumentation"
+        depends on PPC_PSERIES && DEBUG_FS
+        help
+          Adds code to keep track of the number of hypervisor calls made and
+          the amount of time spent in hypervisor callsr.  Wall time spent in
+          each call is always calculated, and if available CPU cycles spent
+          are also calculated.  A directory named hcall_inst is added at the
+          root of the debugfs filesystem.  Within the hcall_inst directory
+          are files that contain CPU specific call statistics.
+
+          This option will add a small amount of overhead to all hypervisor
+          calls.
+
 config DEBUGGER
         bool "Enable debugger hooks"
         depends on DEBUG_KERNEL