=============================================================================

NetBSD 1.6.1 (HZ=256) おけるチューニング結果

-----------------------------------------------------------------------
# ./xps2k -s -w 15
/*
 * usleep() accuracy
 *   I expect usleep(1000) sleeps about less than 8msec...
 *   you may add "HZ=256" in kernel configration
 */
 25.368790sec  usleep( 0*1000)
 25.371059sec  usleep( 1*1000) ---> usleep( 0*1000) sleeps 2.2msec
 25.378857sec  usleep( 2*1000) ---> usleep( 1*1000) sleeps 7.7msec  <==ここ
 25.386670sec  usleep( 3*1000) ---> usleep( 2*1000) sleeps 7.8msec
 25.394484sec  usleep( 4*1000) ---> usleep( 3*1000) sleeps 7.8msec
 25.406200sec  usleep( 5*1000) ---> usleep( 4*1000) sleeps 11.7msec
 25.417922sec  usleep( 6*1000) ---> usleep( 5*1000) sleeps 11.7msec
 25.429641sec  usleep( 7*1000) ---> usleep( 6*1000) sleeps 11.7msec
 25.441357sec  usleep(10*1000) ---> usleep( 7*1000) sleeps 11.7msec
 25.456984sec  usleep(15*1000) ---> usleep(10*1000) sleeps 15.6msec
 25.476513sec  usleep(20*1000) ---> usleep(15*1000) sleeps 19.5msec
 25.503858sec  usleep(30*1000) ---> usleep(20*1000) sleeps 27.3msec
 25.539013sec  usleep(40*1000) ---> usleep(30*1000) sleeps 35.1msec
 25.585891sec                  ---> usleep(40*1000) sleeps 46.8msec

/*
 * wait_half() accuracy
 *   wait_loop is 15
 *   30usec < wait_half()+wait_half() < 50usec, but ...
 */
 25.586274sec
 25.586304sec  --> waits 30usec
 25.586323sec  --> waits 19usec  ===> 49usec  <==ここ と
 25.586341sec  --> waits 18usec  ===> 37usec  <==ここ
 25.586359sec  --> waits 18usec  ===> 36usec
 25.586377sec  --> waits 18usec  ===> 36usec

/*
 * current tty statue
 */
  Line Enable
  Data Terminal Ready
  Request To Send
  Clear To Send
  Data Set Ready
-----------------------------------------------------------------------

=============================================================================