ref: 924634963cc4ee57a57b6801deb572de3f56f8be dir: /sys/src/cmd/1l/cputime.c/
double cputime(void) { long t[4]; long times(long*); int i; times(t); for(i=1; i<4; i++) t[0] += t[i]; return t[0] / 100.; }