a simple hardware detector for latency as well as throughput ver. 0.1.0

The patch is the fist step to test some basic hardware functions like TSC to help people understand if there is any hardware latency as well as throughput problem exposed on bare metal or left behind by BIOS or interfered by SMI. Currently the patch tests TSC, CPU Frequency, and RDRAND, which is a new CPU instruction to get random number introudced in new CPU like Intel Ivy Bridge, in stop_machine context.

The tsc samples (ns) below are from a P4 system. You can change from 0 to 1000 in /sys/kernel/debug/hw_atency_test/threshold to TSC sample at ms.

[root@p4 linux]# rmmod hw_latency_test
[root@p4 linux]# insmod drivers/misc/hw_latency_test.ko [root@p4 linux]# echo tsc > /sys/kernel/debug/hw_latency_test/current [root@p4 linux]# echo 1 > /sys/kernel/debug/hw_latency_test/enable [root@p4 linux]# cat /sys/kernel/debug/hw_latency_test/sample 1340657264.0434121340   388
1340657264.0935125912   379
1340657265.0436123548   404
1340657265.0937122432   441
....
^C
[root@p4 linux]# echo 0 > /sys/kernel/debug/hw_latency_test/enable

Signed-off-by Luming  Yu <[email protected]>

---
I will add more tests after the first patch gets merged for those guys who want to directly play with new hardware functions, and latency and bandwidth is concern, or simply out of curiosity. The patch is based on hardware latency dector written by Jcm in RT-tree. I assume I can add Jcm's signed off here.

 drivers/misc/Kconfig           |    7 +
 drivers/misc/Makefile          |    2 + drivers/misc/hw_latency_test.c |  833 ++++++++++++++++++++++++++++++++++++++++

 3 files changed, 842 insertions(+), 0 deletions(-)

drivers/misc/Kconfig +0 -0

index c779509..a5216b5 100644
@@ -123,6 +123,13 @@ config IBM_ASM

         for information on the specific driver level and support statement for your IBM server.

drivers/misc/Kconfig +7 -0

+config HW_LATENCY_TEST
+       tristate "Testing module to detect hardware lattency and throughput"
+       depends on DEBUG_FS
+       depends on RING_BUFFER
+       depends on X86
+       default m
+

 config PHANTOM
       tristate "Sensable PHANToM (PCI)"
       depends on PCI

drivers/misc/Makefile +0 -0

index 3e1d801..f95c849 100644
@@ -48,4 +48,6 @@ obj-y                         += lis3lv02d/

 obj-y                          += carma/
 obj-$(CONFIG_USB_SWITCH_FSA9480) += fsa9480.o
 obj-$(CONFIG_ALTERA_STAPL)     +=altera-stapl/

drivers/misc/Makefile +2 -0

+obj-$(CONFIG_HW_LATENCY_TEST)  += hw_latency_test.o
+

 obj-$(CONFIG_MAX8997_MUIC)     += max8997-muic.o

drivers/misc/hw_latency_test.c new file +823 -0

new file mode 100644
index 0000000..2aa3a74
@@ -0,0 +1,833 @@
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/ring_buffer.h>
+#include <linux/stop_machine.h>
+#include <linux/time.h>
+#include <linux/hrtimer.h>
+#include <linux/kthread.h>
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+#include <linux/uaccess.h>
+#include <linux/version.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <asm/tlbflush.h>
+
+#define BUF_SIZE_DEFAULT       262144UL
+#define BUF_FLAGS      (RB_FL_OVERWRITE)
+#define        U64STR_SIZE     22
+#define DEBUGFS_BUF_SIZE       1024
+#define DEBUGFS_NAME_SIZE      32
+
+#define        VERSION         "0.1.0"
+#define BANNER         "hardware latency test"
+#define DRVNAME                "hw_latency_test"
+
+#define DEFAULT_SAMPLE_WINDOW  1000000
+#define        DEFAULT_SAMPLE_WIDTH    500000
+#define        DEFAULT_LAT_THRESHOLD   10
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Luming Yu <[email protected]>");
+MODULE_DESCRIPTION("A simple hardware latency test");
+MODULE_VERSION(VERSION);
+
+static int debug;
+static int enabled;
+static int threshold;
+
+module_param(debug, int, 0);
+module_param(enabled, int, 0);
+module_param(threshold, int, 0);
+
+static struct ring_buffer *ring_buffer;
+static DEFINE_MUTEX(ring_buffer_mutex);
+static unsigned long buf_size = 262144UL;
+static struct task_struct *kthread;
+
+struct sample {
+       u64     seqnum;
+       u64     duration;
+       struct timespec timestamp;
+       unsigned long   lost;
+};
+
+static struct data {
+       struct mutex lock;
+       u64     count;
+       u64     max_sample;
+       u64     threshold;
+
+       u64     sample_window;
+       u64     sample_width;
+
+       atomic_t sample_open;
+
+       wait_queue_head_t wq;
+} data;
+
+static ktime_t now;
+struct sample_function {
+       const char *name;
+       struct list_head list;
+       int (*get_sample)(void *unused);
+};
+static struct sample_function *current_sample_func = NULL;
+static LIST_HEAD(sample_function_list);
+static DEFINE_MUTEX(sample_function_mutex);
+static int sample_function_register(struct sample_function *sf);
+static struct dentry *debug_dir;
+
+static int sample_function_register(struct sample_function *sf)
+{
+       struct list_head *entry = &sample_function_list;
+       mutex_lock(&sample_function_mutex);
+       list_add(&sf->list, entry);
+       current_sample_func = sf;
+       mutex_unlock(&sample_function_mutex);
+       return 0;
+}
+
+static int __buffer_add_sample(struct sample *sample)
+{
+       return ring_buffer_write(ring_buffer,
+                               sizeof(struct sample), sample);
+}
+
+static struct sample *buffer_get_sample(struct sample *sample)
+{
+       struct ring_buffer_event *e = NULL;
+       struct sample *s = NULL;
+       unsigned int cpu = 0;
+
+       if (!sample)
+               return NULL;
+
+       mutex_lock(&ring_buffer_mutex);
+       for_each_online_cpu(cpu) {
+               e = ring_buffer_consume(ring_buffer, cpu, NULL, &sample->lost);
+               if (e)
+                       break;
+       }
+       if (e) {
+               s = ring_buffer_event_data(e);
+               memcpy(sample, s, sizeof(struct sample));
+       } else
+               sample = NULL;
+       mutex_unlock(&ring_buffer_mutex);
+       return sample;
+}
+
+static int buffer_add_sample(u64 sample)
+{
+       int ret = 0;
+
+       if (sample > data.threshold) {
+               struct sample s;
+
+               data.count++;
+               s.seqnum = data.count;
+               s.duration = sample;
+               s.timestamp = CURRENT_TIME;
+               ret = __buffer_add_sample(&s);
+
+               if (sample > data.max_sample)
+                       data.max_sample = sample;
+       }
+       return ret;
+}
+
+/*
+ * For new instruction rdrand since Intel Ivy Bridge processor
+ */
+static int get_random_bytes_sample(void *unused)
+{
+       u32 *buffer;
+       ktime_t start, t1, t2;
+       s64     diff, total = 0;
+       u64     sample = 0;
+       int     ret = 1;
+
+       buffer = kzalloc(1024, GFP_KERNEL);
+
+       start = ktime_get();
+       do {
+
+               t1 = ktime_get();
+               get_random_bytes(buffer, 1024);
+               t2 = ktime_get();
+               total = ktime_to_us(ktime_sub(t2, start));
+               diff = ktime_to_us(ktime_sub(t2, t1));
+
+               if (diff < 0) {
+                       printk(KERN_ERR BANNER "time running backwards\n");
+                       goto out;
+               }
+
+               if (diff > sample)
+                       sample = diff;
+
+       } while (total <= data.sample_width);
+
+       ret = buffer_add_sample(sample);
+out:
+       kfree(buffer);
+       return ret;
+}
+
+/*
+ * For cpu frequency testing
+ */
+static int get_freq_sample(void *unused)
+{
+       ktime_t start, t1, t2;
+       s64     diff, total = 0;
+       u32     sample = 0;
+       int     ret = 1;
+       unsigned int cpu_tsc_freq;
+       static DEFINE_MUTEX(freq_pit_mutex);
+
+       start = ktime_get();
+       do {
+               t1 = ktime_get();
+               mutex_lock(&freq_pit_mutex);
+               cpu_tsc_freq = x86_platform.calibrate_tsc();
+               mutex_unlock(&freq_pit_mutex);
+               t2 = ktime_get();
+               total = ktime_to_us(ktime_sub(t2, start));
+               diff = abs(cpu_tsc_freq - tsc_khz);
+
+               if (diff < 0) {
+                       printk(KERN_ERR BANNER "time running backwards\n");
+                       goto out;
+               }
+
+               if (diff > sample)
+                       sample = diff;
+
+       } while (total <= data.sample_width);
+
+       ret = buffer_add_sample(sample);
+out:
+       return ret;
+}
+
+/*
+ * For TSC latency as well as SMI detecting
+ */
+static int get_tsc_sample(void *unused)
+{
+       ktime_t start, t1, t2;
+       s64     diff, total = 0;
+       u64     sample = 0;
+       int     ret = 1;
+
+       now = start = ktime_get();
+       do {
+               t1 = now;
+               now = t2 = ktime_get();
+
+               total = ktime_to_ns(ktime_sub(t2, start));
+               diff = ktime_to_ns(ktime_sub(t2, t1));
+
+               if (diff < 0) {
+                       printk(KERN_ERR BANNER "time running backwards\n");
+                       goto out;
+               }
+
+               if (diff > sample)
+                       sample = diff;
+
+       } while (total <= data.sample_width);
+
+       ret = buffer_add_sample(sample);
+out:
+       return ret;
+}
+
+
+struct sample_function tsc_sample = {
+       .name           = "tsc",
+       .get_sample     = get_tsc_sample,
+};
+
+struct sample_function tsc_freq_sample = {
+       .name           = "freq",
+       .get_sample     = get_freq_sample,
+};
+
+struct sample_function random_bytes_sample = {
+       .name           = "random_bytes",
+       .get_sample     = get_random_bytes_sample,
+};
+
+static int kthread_fn(void *unused)
+{
+       int err = 0;
+       u64 interval = 0;
+       int (*get_sample)(void *unused);
+
+       mutex_lock(&sample_function_mutex);
+       if (current_sample_func)
+               get_sample = current_sample_func->get_sample;
+       else
+               goto out;
+
+       while (!kthread_should_stop()) {
+               mutex_lock(&data.lock);
+
+               err = stop_machine(get_sample, unused, cpu_online_mask);
+               if (err) {
+                       mutex_unlock(&data.lock);
+                       goto err_out;
+               }
+
+               wake_up(&data.wq);
+
+               interval = data.sample_window - data.sample_width;
+               do_div(interval, USEC_PER_MSEC);
+
+               mutex_unlock(&data.lock);
+               if (msleep_interruptible(interval))
+                       goto out;
+       }
+       goto out;
+err_out:
+       printk(KERN_ERR BANNER "could not call stop_machine, disabling\n");
+       enabled = 0;
+out:
+       mutex_unlock(&sample_function_mutex);
+       return err;
+}
+
+static int start_kthread(void)
+{
+       kthread = kthread_run(kthread_fn, NULL, DRVNAME);
+       if (IS_ERR(kthread)) {
+               printk(KERN_ERR BANNER "could not start sampling thread\n");
+               enabled = 0;
+               return -ENOMEM;
+       }
+       return 0;
+}
+
+static int stop_kthread(void)
+{
+       int ret;
+       ret = kthread_stop(kthread);
+       return ret;
+}
+
+static void __reset_stats(void)
+{
+       data.count = 0;
+       data.max_sample = 0;
+       ring_buffer_reset(ring_buffer);
+}
+
+static int init_stats(void)
+{
+       int ret = -ENOMEM;
+
+       mutex_init(&data.lock);
+       init_waitqueue_head(&data.wq);
+       atomic_set(&data.sample_open,0);
+
+       ring_buffer = ring_buffer_alloc(buf_size, BUF_FLAGS);
+
+       if (WARN(!ring_buffer, KERN_ERR BANNER
+               "failed to allocate ring buffer!\n"))
+               goto out;
+       __reset_stats();
+       data.threshold = DEFAULT_LAT_THRESHOLD;
+       data.sample_window = DEFAULT_SAMPLE_WINDOW;
+       data.sample_width = DEFAULT_SAMPLE_WIDTH;
+       ret = 0;
+out:
+       return ret;
+}
+
+static ssize_t simple_data_read(struct file *filp, char __user *ubuf,
+                               size_t cnt, loff_t *ppos, const u64 *entry)
+{
+       char buf[U64STR_SIZE];
+       u64 val = 0;
+       int len = 0;
+
+       memset(buf, 0, sizeof(buf));
+       if (!entry)
+               return -EFAULT;
+       mutex_lock(&data.lock);
+       val = *entry;
+       mutex_unlock(&data.lock);
+       len = snprintf(buf, sizeof(buf), "%llu\n", (unsigned long long)val);
+       return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
+}
+
+static ssize_t simple_data_write(struct file *filp, const char __user *ubuf,
+                               size_t cnt, loff_t *ppos, u64 *entry)
+{
+       char buf[U64STR_SIZE];
+       int csize = min(cnt, sizeof(buf));
+       u64 val = 0;
+       int err = 0;
+
+       memset(buf, '\0', sizeof(buf));
+       if (copy_from_user(buf, ubuf, csize))
+               return -EFAULT;
+       buf[U64STR_SIZE-1] = '\0';
+       err = strict_strtoull(buf, 10, &val);
+       if (err)
+               return -EINVAL;
+       mutex_lock(&data.lock);
+       *entry = val;
+       mutex_unlock(&data.lock);
+       return csize;
+}
+
+#define debug_available_fopen  simple_open
+
+static ssize_t debug_available_fread(struct file *filp, char __user *ubuf,
+                                       size_t  cnt, loff_t *ppos)
+{
+       struct sample_function *sf;
+       ssize_t count = 0;
+       char *buf;
+
+       buf = kzalloc(DEBUGFS_BUF_SIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       mutex_lock(&sample_function_mutex);
+       list_for_each_entry(sf, &sample_function_list, list) {
+               count += snprintf(buf + count,
+                       max((ssize_t)(DEBUGFS_BUF_SIZE - count), (ssize_t)0),
+                       "%s ", sf->name);
+       }
+       mutex_unlock(&sample_function_mutex);
+
+       count += snprintf(buf + count,
+                               max((ssize_t )DEBUGFS_BUF_SIZE - count, (ssize_t) 0),
+                               "\n");
+       count = simple_read_from_buffer(ubuf, cnt, ppos, buf, count);
+       kfree(buf);
+       return count;
+}
+
+#define debug_available_fwrite simple_attr_write
+
+#define debug_available_release        simple_attr_release
+
+#define debug_current_fopen    simple_open
+
+static ssize_t debug_current_fread(struct file *filp, char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       ssize_t count = 0;
+       char *buf;
+
+       buf = kzalloc(DEBUGFS_NAME_SIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       count += snprintf(buf + count,
+               max((ssize_t)DEBUGFS_NAME_SIZE - count, (ssize_t)0),
+                       "%s ", current_sample_func->name);
+       count += snprintf(buf + count,
+                       max((ssize_t)DEBUGFS_NAME_SIZE - count, (ssize_t)0),
+                       "\n");
+       count = simple_read_from_buffer(ubuf, cnt, ppos, buf, count);
+       kfree(buf);
+
+       return count;
+}
+static ssize_t debug_current_fwrite(struct file *filp, const char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       char *buf;
+       ssize_t count;
+       struct sample_function *sf;
+
+       buf = kzalloc(DEBUGFS_NAME_SIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+       count = simple_write_to_buffer(buf, DEBUGFS_NAME_SIZE, ppos, ubuf, cnt);
+       mutex_lock(&sample_function_mutex);
+       list_for_each_entry(sf, &sample_function_list, list) {
+               if (strncmp(sf->name, buf, count-1) !=0)
+                       continue;
+               current_sample_func = sf;
+               break;
+       }
+       mutex_unlock(&sample_function_mutex);
+       return (ssize_t) count;
+}
+#define debug_current_release  simple_attr_release
+
+#define debug_count_fopen      simple_open
+
+static ssize_t debug_count_fread(struct file *filp, char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       return simple_data_read(filp, ubuf, cnt, ppos, &data.count);
+}
+static ssize_t debug_count_fwrite(struct file *filp, const char __user *ubuf,
+                                       size_t cnt,
+                                       loff_t *ppos)
+{
+       return simple_data_write(filp, ubuf, cnt, ppos, &data.count);
+}
+#define debug_count_release    simple_attr_release
+
+#define debug_enable_fopen     simple_open
+
+static ssize_t debug_enable_fread(struct file *filp, char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       char buf[4];
+       if ((cnt < sizeof(buf)) || (*ppos))
+               return 0;
+       buf[0] = enabled ? '1' : '0';
+       buf[1] = '\n';
+       buf[2] = '\0';
+       if (copy_to_user(ubuf, buf, strlen(buf)))
+               return -EFAULT;
+       return *ppos = strlen(buf);
+}
+static ssize_t debug_enable_fwrite(struct file *filp,
+                                       const char __user *ubuf,
+                                       size_t cnt,
+                                       loff_t *ppos)
+{
+       char buf[4];
+       int csize = min(cnt, sizeof(buf));
+       long val = 0;
+       int err = 0;
+
+       memset(buf, '\0', sizeof(buf));
+       if (copy_from_user(buf, ubuf, csize))
+               return -EFAULT;
+       buf[sizeof(buf)-1] = '\0';
+       err = strict_strtoul(buf, 10, &val);
+       if (0 != err)
+               return -EINVAL;
+       if (val) {
+               if (enabled)
+                       goto unlock;
+               enabled = 1;
+               if (start_kthread())
+                       return -EFAULT;
+       } else {
+               if (!enabled)
+                       goto unlock;
+               enabled = 0;
+               err = stop_kthread();
+               if (err) {
+                       printk(KERN_ERR BANNER "cannot stop kthread\n");
+                       return -EFAULT;
+               }
+               wake_up(&data.wq);
+       }
+unlock:
+       return csize;
+}
+#define debug_enable_release   simple_attr_release
+
+#define debug_max_fopen        simple_open
+
+static ssize_t debug_max_fread(struct file *filp, char __user *ubuf,
+                               size_t cnt, loff_t *ppos)
+{
+       return simple_data_read(filp, ubuf, cnt, ppos, &data.max_sample);
+}
+static ssize_t debug_max_fwrite(struct file *filp,
+                               const char __user *ubuf,
+                               size_t  cnt,
+                               loff_t  *ppos)
+{
+       return simple_data_write(filp, ubuf, cnt, ppos, &data.max_sample);
+}
+#define debug_max_release      simple_attr_release
+
+static int debug_sample_fopen(struct inode *inode, struct file *filp)
+{
+       if (!atomic_add_unless(&data.sample_open, 1, 1))
+               return -EBUSY;
+       else
+               return 0;
+}
+static ssize_t debug_sample_fread(struct file *filp, char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       int len = 0;
+       char buf[64];
+       struct sample *sample = NULL;
+
+       if (!enabled)
+               return 0;
+       sample = kzalloc(sizeof(struct sample), GFP_KERNEL);
+       if(!sample)
+               return -ENOMEM;
+
+       while (!buffer_get_sample(sample)) {
+               DEFINE_WAIT(wait);
+               if (filp->f_flags & O_NONBLOCK) {
+                       len = -EAGAIN;
+                       goto out;
+               }
+               prepare_to_wait(&data.wq, &wait, TASK_INTERRUPTIBLE);
+               schedule();
+               finish_wait(&data.wq, &wait);
+               if (signal_pending(current)) {
+                       len = -EINTR;
+                       goto out;
+               }
+               if (!enabled) {
+                       len = 0;
+                       goto out;
+               }
+       }
+       len = snprintf(buf, sizeof(buf), "%010lu.%010lu\t%llu\n",
+                       sample->timestamp.tv_sec,
+                       sample->timestamp.tv_nsec,
+                       sample->duration);
+       if (len > cnt)
+               goto out;
+       if (copy_to_user(ubuf, buf,len))
+               len = -EFAULT;
+out:
+       kfree(sample);
+       return len;
+}
+
+#define debug_sample_fwrite    simple_attr_write
+
+static int debug_sample_release(struct inode *inode, struct file *filp)
+{
+       atomic_dec(&data.sample_open);
+       return 0;
+}
+
+#define debug_threshold_fopen  simple_open
+
+static ssize_t debug_threshold_fread(struct file *filp, char __user *ubuf,
+                                       size_t cnt, loff_t *ppos)
+{
+       return simple_data_read(filp, ubuf, cnt, ppos, &data.threshold);
+}
+static ssize_t debug_threshold_fwrite(struct file *filp,
+                                       const char __user *ubuf,
+                                       size_t cnt,
+                                       loff_t *ppos)
+{
+       int ret;
+       ret = simple_data_write(filp, ubuf, cnt, ppos, &data.threshold);
+       if (enabled)
+               wake_up_process(kthread);
+       return ret;
+}
+#define debug_threshold_release        simple_attr_release
+
+#define debug_width_fopen      simple_open
+
+static ssize_t debug_width_fread(struct file *filp, char __user *ubuf,
+                               size_t cnt, loff_t *ppos)
+{
+       return simple_data_read(filp, ubuf, cnt, ppos, &data.sample_width);
+}
+static ssize_t debug_width_fwrite(struct file *filp,
+                                       const char __user *ubuf,
+                                       size_t cnt,
+                                       loff_t *ppos)
+{
+       char buf[U64STR_SIZE];
+       int csize = min(cnt, sizeof(buf));
+       u64 val = 0;
+       int err = 0;
+
+       memset(buf, '\0', sizeof(buf));
+       if (copy_from_user(buf, ubuf, csize))
+               return -EFAULT;
+       buf[U64STR_SIZE-1] = '\0';
+       err = strict_strtoull(buf, 10, &val);
+       if (0 != err)
+               return -EINVAL;
+       mutex_lock(&data.lock);
+       if (val < data.sample_window)
+               data.sample_width = val;
+       else {
+               mutex_unlock(&data.lock);
+               return -EINVAL;
+       }
+       mutex_unlock(&data.lock);
+       if (enabled)
+               wake_up_process(kthread);
+
+       return csize;
+}
+#define debug_width_release    simple_attr_release
+
+#define debug_window_fopen     simple_open
+
+static ssize_t debug_window_fread(struct file *filp, char __user *ubuf,
+                               size_t cnt, loff_t *ppos)
+{
+       return simple_data_read(filp, ubuf, cnt, ppos, &data.sample_window);
+}
+static ssize_t debug_window_fwrite(struct file *filp,
+                                       const char __user *ubuf,
+                                       size_t cnt,
+                                       loff_t *ppos)
+{
+       char buf[U64STR_SIZE];
+       int csize = min(cnt, sizeof(buf));
+       u64 val = 0;
+       int err = 0;
+
+       memset(buf, '\0', sizeof(buf));
+       if (copy_from_user(buf, ubuf, csize))
+               return -EFAULT;
+       buf[U64STR_SIZE-1] = '\0';
+       err = strict_strtoull(buf, 10, &val);
+       if (0 != err)
+               return -EINVAL;
+       mutex_lock(&data.lock);
+       if (data.sample_width < val)
+               data.sample_window = val;
+       else {
+               mutex_unlock(&data.lock);
+               return -EINVAL;
+       }
+       mutex_unlock(&data.lock);
+       return csize;
+}
+#define debug_window_release   simple_attr_release
+
+#define DEFINE_DEBUGFS_FILE(name)                              \
+       static const struct file_operations name##_fops = {     \
+               .open = debug_##name##_fopen,                   \
+               .read = debug_##name##_fread,                   \
+               .write = debug_##name##_fwrite,                 \
+               .release = debug_##name##_release,              \
+               .owner = THIS_MODULE,                           \
+       };
+
+DEFINE_DEBUGFS_FILE(available)
+DEFINE_DEBUGFS_FILE(current)
+DEFINE_DEBUGFS_FILE(count)
+DEFINE_DEBUGFS_FILE(enable)
+DEFINE_DEBUGFS_FILE(max)
+DEFINE_DEBUGFS_FILE(sample)
+DEFINE_DEBUGFS_FILE(threshold)
+DEFINE_DEBUGFS_FILE(width)
+DEFINE_DEBUGFS_FILE(window)
+
+#undef DEFINE_DEBUGFS_FILE
+
+#undef current
+#define DEFINE_ENTRY(name) {__stringify(name), &name##_fops, NULL},
+
+static struct debugfs_file_table
+{
+       const char      *file_name;
+       const struct file_operations    *fops;
+       struct dentry   *dentry;
+} file_table[] = {
+       DEFINE_ENTRY(available)
+       DEFINE_ENTRY(current)
+       DEFINE_ENTRY(sample)
+       DEFINE_ENTRY(count)
+       DEFINE_ENTRY(max)
+       DEFINE_ENTRY(window)
+       DEFINE_ENTRY(threshold)
+       DEFINE_ENTRY(enable)
+       {NULL, NULL,NULL},
+};
+#undef DEFINE_ENTRY
+
+static int init_debugfs(void)
+{
+       int ret = -ENOMEM;
+       int     i=0;
+
+       debug_dir = debugfs_create_dir(DRVNAME, NULL);
+       if (!debug_dir)
+               goto err_debug_dir;
+
+       while (file_table[i].fops) {
+               file_table[i].dentry =
+                        debugfs_create_file(file_table[i].file_name, 0444,
+                                               debug_dir, NULL,
+                                               file_table[i].fops);
+               if (!file_table[i].dentry)
+                       break;
+               i++;
+       }
+       if (file_table[i].fops) {
+               i--;
+               while (i>=0 && file_table[i].fops && file_table[i].dentry) {
+                       debugfs_remove(file_table[i].dentry);
+                       i--;
+               }
+               debugfs_remove(debug_dir);
+       }
+       ret = 0;
+err_debug_dir:
+       return ret;
+}
+
+static void free_debugfs(void)
+{
+       int i=0;
+
+       while (file_table[i].fops && file_table[i].dentry) {
+               debugfs_remove(file_table[i].dentry);
+               i++;
+       }
+       debugfs_remove(debug_dir);
+}
+
+static int hw_test_init(void)
+{
+       int ret = -ENOMEM;
+
+       printk(KERN_INFO BANNER "version %s\n", VERSION);
+
+       sample_function_register(&tsc_sample);
+       sample_function_register(&tsc_freq_sample);
+       sample_function_register(&random_bytes_sample);
+
+       ret = init_stats();
+       if (0 != ret)
+               goto out;
+       ret = init_debugfs();
+       if (0 != ret)
+               goto err_stats;
+       if (enabled)
+               ret = start_kthread();
+       goto out;
+
+err_stats:
+       ring_buffer_free(ring_buffer);
+out:
+       return ret;
+}
+
+static void hw_test_exit(void)
+{
+       int err;
+
+       if (enabled) {
+               enabled = 0;
+               err = stop_kthread();

Quoted 9 lines · Luming Yu

The patch is the fist step to test some basic hardware functions like TSC to help people understand if there is any hardware latency as well as throughput problem exposed on bare metal or left behind by BIOS or interfered by SMI. Currently the patch tests TSC, CPU Frequency, and RDRAND, which is a new CPU instruction to get random number introudced in new CPU like Intel Ivy Bridge, in stop_machine context.

The tsc samples (ns) below are from a P4 system. You can change from 0 to 1000 in /sys/kernel/debug/hw_atency_test/threshold to TSC sample at ms.

typo.

s/ms/us/

Quoted 37 lines

[root@p4 linux]# rmmod hw_latency_test
[root@p4 linux]# insmod drivers/misc/hw_latency_test.ko [root@p4 linux]# echo tsc > /sys/kernel/debug/hw_latency_test/current [root@p4 linux]# echo 1 > /sys/kernel/debug/hw_latency_test/enable [root@p4 linux]# cat /sys/kernel/debug/hw_latency_test/sample 1340657264.0434121340   388
1340657264.0935125912   379
1340657265.0436123548   404
1340657265.0937122432   441
....
^C
[root@p4 linux]# echo 0 > /sys/kernel/debug/hw_latency_test/enable

Signed-off-by Luming  Yu <[email protected]>

---
I will add more tests after the first patch gets merged for those guys who want to directly play with new hardware functions, and latency and bandwidth is concern, or simply out of curiosity. The patch is based on hardware latency dector written by Jcm in RT-tree. I assume I can add Jcm's signed off here.

 drivers/misc/Kconfig           |    7 +
 drivers/misc/Makefile          |    2 + drivers/misc/hw_latency_test.c |  833 ++++++++++++++++++++++++++++++++++++++++

 3 files changed, 842 insertions(+), 0 deletions(-)

drivers/misc/Kconfig +0 -0

index c779509..a5216b5 100644
@@ -123,6 +123,13 @@ config IBM_ASM

         for information on the specific driver level and support statement for your IBM server.

Quoted 5 lines

+config HW_LATENCY_TEST
+       tristate "Testing module to detect hardware lattency and throughput"
+       depends on DEBUG_FS
+       depends on RING_BUFFER
+       depends on X86

Quoted 52 lines · Luming Yu

Quoted 9 lines · Luming Yu

The patch is the fist step to test some basic hardware functions like TSC to help people understand if there is any hardware latency as well as throughput problem exposed on bare metal or left behind by BIOS or interfered by SMI. Currently the patch tests TSC, CPU Frequency, and RDRAND, which is a new CPU instruction to get random number introudced in new CPU like Intel Ivy Bridge, in stop_machine context.

The tsc samples (ns) below are from a P4 system. You can change from 0 to 1000 in /sys/kernel/debug/hw_atency_test/threshold to TSC sample at ms.

typo.

s/ms/us/

Quoted 37 lines

[root@p4 linux]# rmmod hw_latency_test
[root@p4 linux]# insmod drivers/misc/hw_latency_test.ko [root@p4 linux]# echo tsc > /sys/kernel/debug/hw_latency_test/current [root@p4 linux]# echo 1 > /sys/kernel/debug/hw_latency_test/enable [root@p4 linux]# cat /sys/kernel/debug/hw_latency_test/sample

1340657264.0434121340   388
1340657264.0935125912   379
1340657265.0436123548   404
1340657265.0937122432   441

....
^C
[root@p4 linux]# echo 0 > /sys/kernel/debug/hw_latency_test/enable

Signed-off-by Luming Yu <[email protected]>

---
I will add more tests after the first patch gets merged for those guys who want to directly play with new hardware functions, and latency and bandwidth is concern, or simply out of curiosity. The patch is based on hardware latency dector written by Jcm in RT-tree. I assume I can add Jcm's signed off here.

 drivers/misc/Kconfig           |    7 +
 drivers/misc/Makefile          |    2 +
 drivers/misc/hw_latency_test.c |  833 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 842 insertions(+), 0 deletions(-)

drivers/misc/Kconfig +0 -0

index c779509..a5216b5 100644
@@ -123,6 +123,13 @@ config IBM_ASM
         for information on the specific driver level and support statement
         for your IBM server.
 

Quoted 5 lines

drivers/misc/Kconfig config IBM_ASM · line 130

Quoted 5 lines

drivers/misc/Kconfig +5 -0

+config HW_LATENCY_TEST
+       tristate "Testing module to detect hardware lattency and throughput"
+       depends on DEBUG_FS
+       depends on RING_BUFFER
+       depends on X86

I begun the tool on X86, but bear in mind that use standard kernel interface as much as possible. I was trying to measure CPU Frequency, but the use of calibrate_tsc forced me add a X86 dependency here.

Other finding is recalibrate_cpu_khz() is a null function in SMP. But the only two users (p4-clockmod.c and powernow-k7.c) themselves could lack of users roo these days.

Let me know if there are any other comments.

My plan for the tool is to push it in 3.6 or 3.7. So I will routinely get back to the thread probably weekly or bi-weekly in the time frame. :-)
The 0.2 will based on what I can see in upstream of the tool.

Thanks!!!