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Subject[PATCH 08/13] HW-latency: A stupid memory scanner for raw memory latency test
Date
It's simple memory latency test without any consideration of memory
hierarchy and memory model. It just does simply scan byte by byte.

Signed-off-by: Luming Yu <luming.yu@intel.com>
---
drivers/misc/hw_latency_test.c | 53 ++++++++++++++++++++++++++++++++++++++++--
1 file changed, 51 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/hw_latency_test.c b/drivers/misc/hw_latency_test.c
index 78436da..f47b911 100644
--- a/drivers/misc/hw_latency_test.c
+++ b/drivers/misc/hw_latency_test.c
@@ -46,11 +46,15 @@ static DEFINE_MUTEX(ring_buffer_mutex);
static unsigned long buf_size = 262144UL;
static struct task_struct *kthread;

+static u8 *__start = (u8 *)0xffff880000000000;
+static u8 *__end = (u8 *)0xffffc7ffffffffff;
+
struct sample {
unsigned int cpu;
u64 seqnum;
u64 duration;
struct timespec timestamp;
+ u64 addr;
unsigned long lost;
};

@@ -134,6 +138,7 @@ static int buffer_add_sample(u64 sample)
s.seqnum = data.count;
s.duration = sample;
s.timestamp = CURRENT_TIME;
+ s.addr = (u64) __start;
ret = __buffer_add_sample(&s);

if (sample > data.max_sample)
@@ -247,6 +252,42 @@ out:
return ret;
}

+static int get_mem_sample(void *unused)
+{
+ ktime_t start, t1, t2;
+ s64 diff, total = 0;
+ u64 sample = 0;
+ int ret = 1;
+ u8 temp;
+
+ now = start = ktime_get();
+ do {
+ t1 = now;
+ now = t2 = ktime_get();
+
+ total = ktime_to_ns(ktime_sub(t2, start));
+ temp = *__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;
+
+ if (__start == __end) {
+ __start = (u8 *)0xffff880000000000;
+ printk(KERN_INFO BANNER "one pass finished, jmp to the beginning\n");
+ }
+
+ } while (total <= data.sample_width);
+
+ ret = buffer_add_sample(sample);
+out:
+ return ret;
+}

struct sample_function tsc_sample = {
.name = "tsc",
@@ -266,6 +307,12 @@ struct sample_function random_bytes_sample = {
.get_sample = get_random_bytes_sample,
};

+struct sample_function mem_sample = {
+ .name = "mem",
+ .type = 1,
+ .get_sample = get_mem_sample,
+};
+
static DECLARE_BITMAP(testing_cpu_map, NR_CPUS);

static int kthread_fn(void *unused)
@@ -617,11 +664,12 @@ static ssize_t debug_sample_fread(struct file *filp, char __user *ubuf,
goto out;
}
}
- len = snprintf(buf, sizeof(buf), "[%d]%010lu.%010lu\t%llu\n",
+ len = snprintf(buf, sizeof(buf), "[%d]%010lu.%010lu\t%llu\t[%llx]\n",
sample->cpu,
sample->timestamp.tv_sec,
sample->timestamp.tv_nsec,
- sample->duration);
+ sample->duration,
+ sample->addr);
if (len > cnt)
goto out;
if (copy_to_user(ubuf, buf,len))
@@ -827,6 +875,7 @@ static int hw_test_init(void)
sample_function_register(&tsc_sample);
sample_function_register(&tsc_freq_sample);
sample_function_register(&random_bytes_sample);
+ sample_function_register(&mem_sample);

ret = init_stats();
if (0 != ret)
--
1.7.12.1


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