overlay: Scale the CPU busy value by the numer of active cores

Having 100% always mean one processor fully utilised is much easier to
understand (than having to remember how many cores are on each machine
and scale appropriately).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

overlay/cpu-top.c

@@ -25,10 +25,20 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <string.h>
 #include <errno.h>
 
 #include "cpu-top.h"
 
+int cpu_top_init(struct cpu_top *cpu)
+{
+	memset(cpu, 0, sizeof(*cpu));
+
+	cpu->nr_cpu = sysconf(_SC_NPROCESSORS_ONLN);
+
+	return 0;
+}
+
 int cpu_top_update(struct cpu_top *cpu)
 {
 	struct cpu_stat *s = &cpu->stat[cpu->count++&1];

overlay/cpu-top.h

@@ -29,6 +29,7 @@
 
 struct cpu_top {
 	uint8_t busy;
+	int nr_cpu;
 
 	int count;
 	struct cpu_stat {
@@ -37,6 +38,7 @@ struct cpu_top {
 	} stat[2];
 };
 
+int cpu_top_init(struct cpu_top *cpu);
 int cpu_top_update(struct cpu_top *cpu);
 
 #endif /* CPU_TOP_H */

overlay/overlay.c

@@ -143,8 +143,8 @@ static void init_gpu_top(struct overlay_context *ctx,
 	};
 	int n;
 
+	cpu_top_init(&gt->cpu_top);
 	gpu_top_init(&gt->gpu_top);
-	memset(&gt->cpu, 0, sizeof(gt->cpu));
 
 	chart_init(&gt->cpu, "CPU", 120);
 	chart_set_position(&gt->cpu, PAD, PAD);
@@ -222,7 +222,7 @@ static void show_gpu_top(struct overlay_context *ctx, struct overlay_gpu_top *gt
 	y = PAD + 12 - 2;
 	cairo_set_source_rgba(ctx->cr, 0.75, 0.25, 0.75, 1.);
 	cairo_move_to(ctx->cr, PAD, y);
-	sprintf(txt, "CPU: %3d%% busy", gt->cpu_top.busy);
+	sprintf(txt, "CPU: %3d%% busy", gt->cpu_top.busy * gt->cpu_top.nr_cpu);
 	cairo_show_text(ctx->cr, txt);
 	y += 14;