time 的单调时钟:Sub 和 == 比较为什么不一样

  time.Now().String() 的尾部: m=+0.000114459
  同一个值 Round(0) 之后的完整输出:2026-10-10 13:55:29.982922 +0800 CST
  Round(0) 之前的完整输出:2026-10-10 13:55:29.982922 +0800 CST m=+0.000114459

  time.Now():有 m=
  t.Add(time.Hour):有 m=
  t.AddDate(0,0,1):无 m=
  t.Round(time.Second):无 m=
  t.Truncate(time.Second):无 m=
  t.Round(0):无 m=
  t.UTC():无 m=
  t.Local():无 m=
  t.In(time.UTC):无 m=
  time.Unix(t.Unix(), 0):无 m=
  time.Date(…):无 m=

  t == t.Round(0):false;t.Equal(t.Round(0)):true
  经过 JSON 序列化再反序列化:t == u:false;t.Equal(u):true;t.Sub(u) = 0s(JSON 只保留到纳秒的墙钟时间,单调读数丢了)
  用 time.Time 当 map 的 key:用 t 查 true;用 t.Round(0) 查 false(同一个时刻!)
  同一时刻、不同时区:d == l:false;d.Equal(l):true

  time.Now() 32 ns/次;time.Since(t) 15 ns/次;t.Round(0) 2 ns/次

  The general rule is that the wall clock is for telling time and the monotonic clock is for measuring time.
  The canonical way to strip a monotonic clock reading is to use t = t.Round(0).
  If Times t and u both contain monotonic clock readings, the operations t.After(u), t.Before(u), t.Equal(u), t.Compare(u), and t.Sub(u) are carried out using the monotonic clock readings alone, ignoring the wall clock readings. If either t or u contains no monotonic clock reading, these operations fall back to using the wall clock readings.
  On some systems the monotonic clock will stop if the computer goes to sleep.
  Note that the Go == operator compares not just the time instant but also the Location and the monotonic clock reading. See the documentation for the Time type for a discussion of equality testing for Time values.  For debugging, the result of t.String does include the monotonic clock reading if present. If t != u because of different monotonic clock readings, that difference will be visible when printing t.String() and u.String().