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[PATCH] MIPS: crazy spinlock speed test.

To: linux-mips@linux-mips.org, ralf@linux-mips.org
Subject: [PATCH] MIPS: crazy spinlock speed test.
From: David Daney <ddaney@caviumnetworks.com>
Date: Tue, 16 Feb 2010 15:26:35 -0800
Cc: David Daney <ddaney@caviumnetworks.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
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>
---
 arch/mips/Kconfig.debug          |    7 ++
 arch/mips/kernel/Makefile        |    1 +
 arch/mips/kernel/spinlock_test.c |  141 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 149 insertions(+), 0 deletions(-)
 create mode 100644 arch/mips/kernel/spinlock_test.c

diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index d8c0fd7..8354a18 100644
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -131,4 +131,11 @@ 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
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 642ae95..aac78e3 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_GPIO_TXX9)               += gpio_txx9.o
 
 obj-$(CONFIG_KEXEC)            += machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_EARLY_PRINTK)     += early_printk.o
+obj-$(CONFIG_SPINLOCK_TEST)    += spinlock_test.o
 
 CFLAGS_cpu-bugs64.o    = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o 
/dev/null -xc /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
 
diff --git a/arch/mips/kernel/spinlock_test.c b/arch/mips/kernel/spinlock_test.c
new file mode 100644
index 0000000..da61134
--- /dev/null
+++ b/arch/mips/kernel/spinlock_test.c
@@ -0,0 +1,141 @@
+#include <linux/init.h>
+#include <linux/kthread.h>
+#include <linux/hrtimer.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+
+
+static int ss_get(void *data, u64 *val)
+{
+       ktime_t start, finish;
+       int loops;
+       int cont;
+       DEFINE_RAW_SPINLOCK(ss_spin);
+
+       loops = 1000000;
+       cont = 1;
+
+       start = ktime_get();
+
+       while (cont) {
+               raw_spin_lock(&ss_spin);
+               loops--;
+               if (loops == 0)
+                       cont = 0;
+               raw_spin_unlock(&ss_spin);
+       }
+
+       finish = ktime_get();
+
+       *val = ktime_us_delta(finish, start);
+
+       return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_ss, ss_get, NULL, "%llu\n");
+
+
+
+struct spin_multi_state {
+       raw_spinlock_t lock;
+       atomic_t start_wait;
+       atomic_t enter_wait;
+       atomic_t exit_wait;
+       int loops;
+};
+
+struct spin_multi_per_thread {
+       struct spin_multi_state *state;
+       ktime_t start;
+};
+
+static int multi_other(void *data)
+{
+       int loops;
+       int cont;
+       struct spin_multi_per_thread *pt = data;
+       struct spin_multi_state *s = pt->state;
+
+       loops = s->loops;
+       cont = 1;
+
+       atomic_dec(&s->enter_wait);
+
+       while (atomic_read(&s->enter_wait))
+               ; /* spin */
+
+       pt->start = ktime_get();
+
+       atomic_dec(&s->start_wait);
+
+       while (atomic_read(&s->start_wait))
+               ; /* spin */
+
+       while (cont) {
+               raw_spin_lock(&s->lock);
+               loops--;
+               if (loops == 0)
+                       cont = 0;
+               raw_spin_unlock(&s->lock);
+       }
+
+       atomic_dec(&s->exit_wait);
+       while (atomic_read(&s->exit_wait))
+               ; /* spin */
+       return 0;
+}
+
+static int multi_get(void *data, u64 *val)
+{
+       ktime_t finish;
+       struct spin_multi_state ms;
+       struct spin_multi_per_thread t1, t2;
+
+       ms.lock = __RAW_SPIN_LOCK_UNLOCKED("multi_get");
+       ms.loops = 1000000;
+
+       atomic_set(&ms.start_wait, 2);
+       atomic_set(&ms.enter_wait, 2);
+       atomic_set(&ms.exit_wait, 2);
+       t1.state = &ms;
+       t2.state = &ms;
+
+       kthread_run(multi_other, &t2, "multi_get");
+
+       multi_other(&t1);
+
+       finish = ktime_get();
+
+       *val = ktime_us_delta(finish, t1.start);
+
+       return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_multi, multi_get, NULL, "%llu\n");
+
+
+extern struct dentry *mips_debugfs_dir;
+static int __init spinlock_test(void)
+{
+       struct dentry *d;
+
+       if (!mips_debugfs_dir)
+               return -ENODEV;
+
+       d = debugfs_create_file("spin_single", S_IRUGO,
+                               mips_debugfs_dir, NULL,
+                               &fops_ss);
+       if (!d)
+               return -ENOMEM;
+
+       d = debugfs_create_file("spin_multi", S_IRUGO,
+                               mips_debugfs_dir, NULL,
+                               &fops_multi);
+       if (!d)
+               return -ENOMEM;
+
+       return 0;
+}
+device_initcall(spinlock_test);
-- 
1.6.6


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