2 files changed, 24 insertions, 20 deletions

diff --git a/lib/libc/gen/sleep.3 b/lib/libc/gen/sleep.3
index ab7e6f0a9c29f..22a0ab57fff04 100644
--- a/lib/libc/gen/sleep.3
+++ b/lib/libc/gen/sleep.3
@@ -53,7 +53,9 @@ System activity or time spent in processing the
 call may lengthen the sleep by a second.
 .Pp
 If a timer is already running on the process its state is unaltered by
-this sleep implementation.
+this
+.Fn sleep
+implementation.
 If the value
 .Fa seconds
 is more than or equal to the remaining clock time for the running timer,
@@ -65,10 +67,10 @@ This function is implemented using
 by pausing for
 .Fa seconds
 of time or until any signal occurse.
-For compatibility reasons during
+For compatibility reasons SIGALRM signal unblocked and handled
+internally during
 .Fn sleep
-call SIGALRM handler is temporary set to the
-function which does nothing but returns.
+call.
 .Sh RETURN VALUES
 The
 .Fn sleep
@@ -79,8 +81,11 @@ needed to be passed to a subsequent sleep to complete the necessary delay.
 repeatedly until it returns zero may busy-wait until a timer
 is available.
 .Sh SEE ALSO
+.Xr alarm 3 ,
+.Xr setitimer 2 ,
 .Xr signal 3 ,
 .Xr signanosleep 2 ,
+.Xr ualarm 3 ,
 .Xr usleep 3
 .Sh HISTORY
 A
diff --git a/lib/libc/gen/usleep.3 b/lib/libc/gen/usleep.3
index 66b317a3b704f..5b539f996788d 100644
--- a/lib/libc/gen/usleep.3
+++ b/lib/libc/gen/usleep.3
@@ -52,30 +52,29 @@ of time.
 System activity or time spent in processing the
 call may lengthen the sleep slightly.
 .Pp
-If a timer is already running on the process its state is saved.
+If a timer is already running on the process its state is unaltered by
+this
+.Fn usleep
+implementation.
 If the value
 .Fa microseconds
-is more than or equal to the remaining clock time for the saved timer,
+is more than or equal to the remaining clock time for the running timer,
 the sleep time is set to
 the remaining clock time.
-The state of the previous timer
-is restored after
+.Pp
+This function is implemented using
+.Xr signanosleep 2
+by pausing for
 .Fa microseconds
-has passed.
+of time or until SIGALRM signal occurse.
+.Sh NOTES
 .Pp
-This routine is implemented using 
-.Xr setitimer 2 ;
-it requires eight system calls each time it is invoked.
-A similar but less compatible function can be obtained with a single
-.Xr select 2 ;
-such a function would not restart after signals, but would not interfere
-with other uses of
-.Xr setitimer .
+A microsecond is 0.000001 seconds.
 .Sh SEE ALSO
-.Xr getitimer 2 ,
-.Xr setitimer 2 ,
-.Xr sigpause 2 ,
 .Xr alarm 3 ,
+.Xr setitimer 2 ,
+.Xr signal 3 ,
+.Xr signanosleep 2 ,
 .Xr sleep 3 ,
 .Xr ualarm 3
 .Sh HISTORY