Improve example for "Can a thread's priority change while it is on the

[pintos-anon] / doc / threads.texi

diff --git a/doc/threads.texi b/doc/threads.texi
index 1231168e34224ab3aca2ee50479087ceb0abdf46..f1fd4dffbb0e4061be96b2104680a8f30ce13685 100644 (file)
--- a/doc/threads.texi
+++ b/doc/threads.texi
@@ -524,7 +524,7 @@ scheduler
 with the @option{-mlfqs} kernel option.  Passing this
 option sets @code{thread_mlfqs}, declared in @file{threads/thread.h}, to
 true when the options are parsed by @func{parse_options}, which happens
-midway through @func{main}.
+early in @func{main}.
 
 When the 4.4@acronym{BSD} scheduler is enabled, threads no longer
 directly control their own priorities.  The @var{priority} argument to
@@ -740,11 +740,9 @@ to thread @var{B} (with priority 3), then @var{B}'s new priority is 5, not 8.
 
 @item Can a thread's priority change while it is on the ready queue?
 
-Yes.  Consider this case: low-priority thread @var{L} holds a
-lock that high-priority thread @var{H} wants, so @var{H} donates its
-priority to @var{L}.  @var{L} releases the lock and
-thus loses the CPU and is moved to the ready queue.  Now @var{L}'s
-old priority is restored while it is in the ready queue.
+Yes.  Consider a ready, low-priority thread @var{L} that holds a lock.
+High-priority thread @var{H} attempts to acquire the lock and blocks,
+thereby donating its priority to ready thread @var{L}.
 
 @item Can a thread's priority change while it is blocked?
 
@@ -768,14 +766,6 @@ becomes the higher of the newly set priority or the highest donated
 priority.  When the donations are released, the thread's priority
 becomes the one set through the function call.  This behavior is checked
 by the @code{priority-donate-lower} test.
-
-@item Calling @func{printf} in @func{sema_up} or @func{sema_down} reboots!
-
-@anchor{printf Reboots}
-Yes.  These functions are called before @func{printf} is ready to go.
-You could add a global flag initialized to false and set it to true
-just before the first @func{printf} in @func{main}.  Then modify
-@func{printf} itself to return immediately if the flag isn't set.
 @end table
 
 @node Advanced Scheduler FAQ