ref: 82f0a1d2b47c3d1d7cf573a9f5008f95ddf3d092 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.; }