MIPS: Crazy spinlock speed test.

This is just a test program for raw_spinlocks.  The main reason I
wrote it is to validate my spinlock changes that I sent in a previous
patch.

To use it enable CONFIG_DEBUG_FS and CONFIG_SPINLOCK_TEST then at run
time do:

# mount -t debugfs none /sys/kernel/debug/
# cat /sys/kernel/debug/mips/spin_single
# cat /sys/kernel/debug/mips/spin_multi

On my 600MHz octeon cn5860 (16 CPUs) I get

		spin_single	spin_multi
base		106885		247941
spinlock_patch	75194		219465

This shows that for uncontended locks the spinlock patch gives 41%
improvement and for contended locks 12% improvement (1/time).

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/969/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 32a010d5edb9..43dc27997730 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -121,4 +121,11 @@ config DEBUG_ZBOOT
           to reduce the kernel image size and speed up the booting procedure a
           little.
 
+config SPINLOCK_TEST
+        bool "Enable spinlock timing tests in debugfs"
+        depends on DEBUG_FS
+        default n
+        help
+          Add several files to the debugfs to test spinlock speed.
+
 endmenu