Commit bba90760 authored by David Daney's avatar David Daney Committed by Ralf Baechle

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: default avatarDavid Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/969/Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 500c2e1f
......@@ -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
......@@ -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)
......
#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);
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