cx_usage

[YONETANI Tomokazu]

Hello.

On Wed, Jun 16, 2004 at 10:10:55PM +0900, YONETANI Tomokazu wrote:
> What do you think about the following changes?
> 
> - print 100% instead of 99% when there's only 1 Cx state, and 0%
>   when the sum is zero.
> - two digits from fractional part of each percentage are shown;
>   my Laptop PC barely enters into C3 state and hw.acpi.cpu.cx_usage
>   is almost always "0% 99% 0%" after revision 1.39. it's now shown as
>   "0.00% 99.96% 0.03%"

Actually, cpu_cx_stats[i] * 100 may not fit in u_int and would print
incorrect value as values grow. Please try this instead.

--- /home/build/freebsd/current/sys/dev/acpica/acpi_cpu.c	2004-06-16 15:27:25.000000000 +0900
+++ acpi_cpu.c	2004-06-16 15:24:38.000000000 +0900
@@ -1046,15 +1051,22 @@
     struct sbuf	 sb;
     char	 buf[128];
     int		 i;
-    u_int	 sum;
+    u_int64_t	 frac, real, sum;
 
-    /* Avoid divide by 0 potential error. */
-    sum = 1;
+    sum = 0;
     for (i = 0; i < cpu_cx_count; i++)
 	sum += cpu_cx_stats[i];
     sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
-    for (i = 0; i < cpu_cx_count; i++)
-	sbuf_printf(&sb, "%u%% ", (cpu_cx_stats[i] * 100) / sum);
+    for (i = 0; i < cpu_cx_count; i++) {
+	if (sum == 0)
+	    sbuf_printf(&sb, "0%% ");
+	else {
+	    real = cpu_cx_stats[i] * 100;
+	    frac = (real % sum) * 100;
+	    sbuf_printf(&sb, "%u.%02u%% ",
+		(u_int)(real / sum), (u_int)(frac / sum));
+	}
+    }
     sbuf_trim(&sb);
     sbuf_finish(&sb);
     sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);