Invert the priority scheme, so that PRI_MIN is now the lowest priority

[pintos-anon] / doc / threads.texi

diff --git a/doc/threads.texi b/doc/threads.texi
index 1093f335636dcc13c85e3bebe944129d97c7beae..d83b52f4525770b2a89d7768713426e1ad1821b0 100644 (file)
--- a/doc/threads.texi
+++ b/doc/threads.texi
@@ -76,11 +76,11 @@ assembly code.  (You don't have to understand it.)  It saves the
 state of the currently running thread and restores the state of the
 thread we're switching to.
 
 state of the currently running thread and restores the state of the
 thread we're switching to.
 

-Using the @command{gdb} debugger, slowly trace through a context
-switch to see what happens (@pxref{gdb}).  You can set a
+Using the GDB debugger, slowly trace through a context
+switch to see what happens (@pxref{GDB}).  You can set a

 breakpoint on @func{schedule} to start out, and then
 breakpoint on @func{schedule} to start out, and then

-single-step from there.@footnote{@command{gdb} might tell you that
-@func{schedule} doesn't exist, which is arguably a @command{gdb} bug.
+single-step from there.@footnote{GDB might tell you that
+@func{schedule} doesn't exist, which is arguably a GDB bug.

 You can work around this by setting the breakpoint by filename and
 line number, e.g.@: @code{break thread.c:@var{ln}} where @var{ln} is
 the line number of the first declaration in @func{schedule}.}  Be sure
 You can work around this by setting the breakpoint by filename and
 line number, e.g.@: @code{break thread.c:@var{ln}} where @var{ln} is
 the line number of the first declaration in @func{schedule}.}  Be sure


@@ -185,8 +185,8 @@ project 3.  For now, you can ignore it.
 
 @item flags.h
 Macros that define a few bits in the 80@var{x}86 ``flags'' register.
 
 @item flags.h
 Macros that define a few bits in the 80@var{x}86 ``flags'' register.

-Probably of no interest.  See @bibref{IA32-v1}, section 3.4.3, for more
-information.
+Probably of no interest.  See @bibref{IA32-v1}, section 3.4.3, ``EFLAGS
+Register,'' for more information.

 @end table
 
 @menu
 @end table
 
 @menu


@@ -328,9 +328,10 @@ timer ticks or input events.  Turning off interrupts also increases the
 interrupt handling latency, which can make a machine feel sluggish if
 taken too far.
 
 interrupt handling latency, which can make a machine feel sluggish if
 taken too far.
 

-You may need to add or modify code where interrupts are already
-disabled, such as in @func{sema_up} or @func{sema_down}.  You should
-still try to keep this code as short as you can.
+The synchronization primitives themselves in @file{synch.c} are
+implemented by disabling interrupts.  You may need to increase the
+amount of code that runs with interrupts disabled here, but you should
+still try to keep it to a minimum.

 
 Disabling interrupts can be useful for debugging, if you want to make
 sure that a section of code is not interrupted.  You should remove
 
 Disabling interrupts can be useful for debugging, if you want to make
 sure that a section of code is not interrupted.  You should remove


@@ -441,8 +442,8 @@ priority such that it no longer has the highest priority must cause it
 to immediately yield the CPU.
 
 Thread priorities range from @code{PRI_MIN} (0) to @code{PRI_MAX} (63).
 to immediately yield the CPU.
 
 Thread priorities range from @code{PRI_MIN} (0) to @code{PRI_MAX} (63).

-Lower numbers correspond to @emph{higher} priorities, so that priority 0
-is the highest priority and priority 63 is the lowest.
+Lower numbers correspond to lower priorities, so that priority 0
+is the lowest priority and priority 63 is the highest.

 The initial thread priority is passed as an argument to
 @func{thread_create}.  If there's no reason to choose another
 priority, use @code{PRI_DEFAULT} (31).  The @code{PRI_} macros are
 The initial thread priority is passed as an argument to
 @func{thread_create}.  If there's no reason to choose another
 priority, use @code{PRI_DEFAULT} (31).  The @code{PRI_} macros are


@@ -511,7 +512,8 @@ must be active, but we must be able to choose the 4.4@acronym{BSD}
 scheduler
 with the @option{-mlfqs} kernel option.  Passing this
 option sets @code{enable_mlfqs}, declared in @file{threads/init.h}, to
 scheduler
 with the @option{-mlfqs} kernel option.  Passing this
 option sets @code{enable_mlfqs}, declared in @file{threads/init.h}, to

-true.
+true when the options are parsed by @func{parse_options}, which happens
+midway through @func{main}.

 
 When the 4.4@acronym{BSD} scheduler is enabled, threads no longer
 directly control their own priorities.  The @var{priority} argument to
 
 When the 4.4@acronym{BSD} scheduler is enabled, threads no longer
 directly control their own priorities.  The @var{priority} argument to


@@ -531,6 +533,12 @@ Here's a summary of our reference solution, produced by the
 @command{diffstat} program.  The final row gives total lines inserted
 and deleted; a changed line counts as both an insertion and a deletion.
 
 @command{diffstat} program.  The final row gives total lines inserted
 and deleted; a changed line counts as both an insertion and a deletion.
 

+The reference solution represents just one possible solution.  Many
+other solutions are also possible and many of those differ greatly from
+the reference solution.  Some excellent solutions may not modify all the
+files modified by the reference solution, and some may modify files not
+modified by the reference solution.
+

 @verbatim
  devices/timer.c       |   42 +++++-
  threads/fixed-point.h |  120 ++++++++++++++++++
 @verbatim
  devices/timer.c       |   42 +++++-
  threads/fixed-point.h |  120 ++++++++++++++++++


@@ -540,6 +548,8 @@ and deleted; a changed line counts as both an insertion and a deletion.
  5 files changed, 440 insertions(+), 29 deletions(-)
 @end verbatim
 
  5 files changed, 440 insertions(+), 29 deletions(-)
 @end verbatim
 

+@file{fixed-point.h} is a new file added by the reference solution.
+

 @item How do I update the @file{Makefile}s when I add a new source file?
 
 @anchor{Adding Source Files}
 @item How do I update the @file{Makefile}s when I add a new source file?
 
 @anchor{Adding Source Files}


@@ -717,4 +727,12 @@ just before the first @func{printf} in @func{main}.  Then modify
 
 It doesn't have to.  We won't test priority donation and the advanced
 scheduler at the same time.
 
 It doesn't have to.  We won't test priority donation and the advanced
 scheduler at the same time.

+
+@item Can I use one queue instead of 64 queues?
+
+Yes, that's fine.  It's easiest to describe the algorithm in terms of 64
+separate queues, but that doesn't mean you have to implement it that
+way.
+
+If you use a single queue, it should probably be sorted.

 @end table
 @end table