1 files changed, 44 insertions, 0 deletions
diff --git a/overlay/cpu-top.c b/overlay/cpu-top.c
new file mode 100644
index 00000000..ccfc9a6b
--- /dev/null
+++ b/overlay/cpu-top.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "cpu-top.h"
+
+int cpu_top_update(struct cpu_top *cpu)
+{
+	struct cpu_stat *s = &cpu->stat[cpu->count++&1];
+	struct cpu_stat *d = &cpu->stat[cpu->count&1];
+	uint64_t d_total, d_idle;
+	char buf[4096];
+	int fd, len = -1;
+
+	fd = open("/proc/stat", 0);
+	if (fd < 0)
+		return errno;
+
+	len = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+
+	if (len < 0)
+		return EIO;
+	buf[len] = '\0';
+
+#ifdef __x86_64__
+	sscanf(buf, "cpu %lu %lu %lu %lu",
+	       &s->user, &s->nice, &s->sys, &s->idle);
+#else
+	sscanf(buf, "cpu %llu %llu %llu %llu",
+	       &s->user, &s->nice, &s->sys, &s->idle);
+#endif
+
+	s->total = s->user + s->nice + s->sys + s->idle;
+	if (cpu->count == 1)
+		return EAGAIN;
+
+	d_total = s->total - d->total;
+	d_idle = s->idle - d->idle;
+	cpu->busy = 100 - 100 * d_idle / d_total;
+
+	return 0;
+}