TASK5: Implement the solution with time in userspace and kernel space

05_timers/kernel_module/Makefile

@@ -0,0 +1,9 @@
+KERNELDIR ?= ../../../buildroot/buildroot-2021.02.7/output/build/linux-5.10.7/ #WARNING relative path
+
+obj-m := mytimeobj.o
+
+all:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KERNELDIR) M=$(PWD) clean

05_timers/kernel_module/mytimeobj.c

@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/module.h>
+#include <linux/kobject.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/ktime.h>
+
+MODULE_AUTHOR("Nazarii Kurylko <kurylko.n@gmail.com>");
+MODULE_DESCRIPTION("time in kernel module");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.1");
+
+static ssize_t time_prev_call_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *buf)
+{
+	static struct timespec64 ts_prev;
+	ssize_t count;
+
+	count = scnprintf(buf, PAGE_SIZE, "%llds.%ldns\n", ts_prev.tv_sec,
+			  ts_prev.tv_nsec);
+
+	ktime_get_real_ts64(&ts_prev);
+	return count;
+}
+
+static ssize_t time_since_prev_call_show(struct kobject *kobj,
+					 struct kobj_attribute *attr, char *buf)
+{
+	struct timespec64 ts;
+	ktime_t now = 0;
+	static int inited;
+	static ktime_t prev;
+
+	now = ktime_get();
+	if (!inited) {
+		prev = now;
+		inited = 1;
+	}
+
+	now = ktime_get();
+	ts = ktime_to_timespec64(ktime_sub(now, prev));
+	prev = now;
+
+	return scnprintf((char *)buf, PAGE_SIZE, "%llds.%ldns\n", ts.tv_sec,
+			 ts.tv_nsec);
+}
+
+static struct kobj_attribute attribute1 =
+	__ATTR(time_prev_call, 0444, time_prev_call_show, NULL);
+
+static struct kobj_attribute attribute2 =
+	__ATTR(time_since_prev_call, 0444, time_since_prev_call_show, NULL);
+
+static struct kobject *myobject_kobj;
+
+static struct attribute *attrs[] = {
+	&attribute1.attr, &attribute2.attr, NULL,
+	/* need to NULL terminate the list of attributes */
+};
+
+static struct attribute_group attr_group = {
+	.attrs = attrs,
+};
+
+static int myobject_init(void)
+{
+	int res = 0;
+
+	myobject_kobj = kobject_create_and_add("MyTimeObject", kernel_kobj);
+	if (!myobject_kobj)
+		return -ENOMEM;
+	res = sysfs_create_group(myobject_kobj, &attr_group);
+	if (res)
+		kobject_put(myobject_kobj);
+
+	return res;
+}
+
+static void myobject_exit(void)
+{
+	kobject_put(myobject_kobj);
+}
+
+module_init(myobject_init);
+module_exit(myobject_exit);

05_timers/userspace_time/Makefile

@@ -0,0 +1,11 @@
+default: mytime
+
+rpscissors.o: mytime.c
+	gcc -c mytime.c -o mytime.o
+
+rpscissors: mytime.o
+	gcc mytime.o -o mytime 
+
+clean:
+	-rm -f mytime.o
+	-rm -f mytime

05_timers/userspace_time/mytime.c

@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: 0BSD
+/**
+ * Description: My Time
+ * Author:      Nazarii Kurylko
+ * Created:     09.12.2021
+ **/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <string.h>
+
+#define ARRAY_SIZE(a) (sizeof(a) / sizeof((a)[0]))
+
+// see https://man7.org/linux/man-pages/man3/clock_gettime.3.html for details
+
+clockid_t clk_id_arr[] = { CLOCK_REALTIME,	  CLOCK_REALTIME_ALARM,
+			   CLOCK_REALTIME_COARSE,   CLOCK_TAI,
+			   CLOCK_MONOTONIC,	 CLOCK_MONOTONIC_RAW,
+			   CLOCK_MONOTONIC_COARSE,  CLOCK_PROCESS_CPUTIME_ID,
+			   CLOCK_THREAD_CPUTIME_ID, CLOCK_BOOTTIME,
+			   CLOCK_BOOTTIME_ALARM };
+
+char *clk_id_arr_str[] = {
+	"CLOCK_REALTIME",	       "CLOCK_REALTIME_ALARM",
+	"CLOCK_REALTIME_COARSE",   "CLOCK_TAI",
+	"CLOCK_MONOTONIC",	       "CLOCK_MONOTONIC_RAW",
+	"CLOCK_MONOTONIC_COARSE",  "CLOCK_PROCESS_CPUTIME_ID",
+	"CLOCK_THREAD_CPUTIME_ID", "CLOCK_BOOTTIME",
+	"CLOCK_BOOTTIME_ALARM"
+};
+
+int timespec2str(char *buf, uint len, struct timespec *ts)
+{
+	int ret;
+	struct tm t;
+
+	tzset();
+	if (localtime_r(&(ts->tv_sec), &t) == NULL)
+		return 1;
+
+	ret = strftime(buf, len, "%F %T", &t);
+	if (ret == 0)
+		return 2;
+	len -= ret - 1;
+
+	ret = snprintf(&buf[strlen(buf)], len, ".%09ld", ts->tv_nsec);
+	if (ret >= len)
+		return 3;
+
+	return 0;
+}
+
+/*main algorithm*/
+int main(int argc, char **argv)
+{
+	static int i;
+	static struct timespec mytime, mytimeres;
+	char tmp[100];
+
+	for (i = 0; i < ARRAY_SIZE(clk_id_arr); ++i) {
+		//print clock output
+		if (!clock_gettime(clk_id_arr[i], &mytime))
+			printf("%s: time: %ld sec, %ld nsec\n",
+			       clk_id_arr_str[i], mytime.tv_sec,
+			       mytime.tv_nsec);
+		//print time in formated string
+		timespec2str(tmp, sizeof(tmp), &mytime);
+		printf("%s: %s\n", clk_id_arr_str[i], tmp);
+
+		//print clock resolution
+		if (!clock_getres(clk_id_arr[i], &mytimeres))
+			printf("%s: resolution: %ld sec, %ld nsec\n",
+			       clk_id_arr_str[i], mytimeres.tv_sec,
+			       mytimeres.tv_nsec);
+		printf("==================================\n");
+	}
+
+	return 0;
+}