-@node Project 1--Threads, Project 2--User Programs, Pintos Tour, Top
+@node Project 1--Threads
@chapter Project 1: Threads
In this assignment, we give you a minimally functional thread system.
Before you read the description of this project, you should read all of
the following sections: @ref{Introduction}, @ref{Coding Standards},
@ref{Debugging Tools}, and @ref{Development Tools}. You should at least
-skim the material in @ref{Threads Tour} and especially
-@ref{Synchronization}. To complete this project you will also need to
-read @ref{4.4BSD Scheduler}.
+skim the material from @ref{Pintos Loading} through @ref{Memory
+Allocation}, especially @ref{Synchronization}. To complete this project
+you will also need to read @ref{4.4BSD Scheduler}.
@menu
* Project 1 Background::
@item thread.c
@itemx thread.h
-Basic thread support. Much of your work will take place in these
-files. @file{thread.h} defines @struct{thread}, which you are likely
-to modify in all four projects. See @ref{struct thread} and @ref{Thread
-Support} for more information.
+Basic thread support. Much of your work will take place in these files.
+@file{thread.h} defines @struct{thread}, which you are likely to modify
+in all four projects. See @ref{struct thread} and @ref{Threads} for
+more information.
@item switch.S
@itemx switch.h
Functions for I/O port access. This is mostly used by source code in
the @file{devices} directory that you won't have to touch.
-@item mmu.h
-Functions and macros related to memory management, including page
-directories and page tables. This will be more important to you in
-project 3. For now, you can ignore it.
+@item vaddr.h
+@itemx pte.h
+Functions and macros for working with virtual addresses and page table
+entries. These will be more important to you in project 3. For now,
+you can ignore them.
@item flags.h
Macros that define a few bits in the 80@var{x}86 ``flags'' register.
@item serial.c
@itemx serial.h
Serial port driver. Again, @func{printf} calls this code for you,
-so you don't need to do so yourself. Feel free to look through it if
-you're curious.
+so you don't need to do so yourself.
+It handles serial input by passing it to the input layer (see below).
@item disk.c
@itemx disk.h
Supports reading and writing sectors on up to 4 IDE disks. This won't
actually be used until project 2.
+@item kbd.c
+@itemx kbd.h
+Keyboard driver. Handles keystrokes passing them to the input layer
+(see below).
+
+@item input.c
+@itemx input.h
+Input layer. Queues input characters passed along by the keyboard or
+serial drivers.
+
@item intq.c
@itemx intq.h
Interrupt queue, for managing a circular queue that both kernel
You are probably looking at a backtrace that looks something like this:
@example
-0xc0108810: debug_panic (../../lib/kernel/debug.c:32)
-0xc010a99f: pass (../../tests/threads/tests.c:93)
-0xc010bdd3: test_mlfqs_load_1 (../../tests/threads/mlfqs-load-1.c:33)
-0xc010a8cf: run_test (../../tests/threads/tests.c:51)
-0xc0100452: run_task (../../threads/init.c:283)
-0xc0100536: run_actions (../../threads/init.c:333)
-0xc01000bb: main (../../threads/init.c:137)
+0xc0108810: debug_panic (lib/kernel/debug.c:32)
+0xc010a99f: pass (tests/threads/tests.c:93)
+0xc010bdd3: test_mlfqs_load_1 (...threads/mlfqs-load-1.c:33)
+0xc010a8cf: run_test (tests/threads/tests.c:51)
+0xc0100452: run_task (threads/init.c:283)
+0xc0100536: run_actions (threads/init.c:333)
+0xc01000bb: main (threads/init.c:137)
@end example
This is just confusing output from the @command{backtrace} program. It
@item If the highest-priority thread yields, does it continue running?
-Yes. As long as there is a single highest-priority thread, it continues
+Yes. If there is a single highest-priority thread, it continues
running until it blocks or finishes, even if it calls
@func{thread_yield}.
If multiple threads have the same highest priority,
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.
+@item Can a thread's priority change while it is blocked?
+
+Yes. While a thread that has acquired lock @var{L} is blocked for any
+reason, its priority can increase by priority donation if a
+higher-priority thread attempts to acquire @var{L}. This case is
+checked by the @code{priority-donate-sema} test.
+
@item Can a thread added to the ready list preempt the processor?
Yes. If a thread added to the ready list has higher priority than the
@item How does @func{thread_set_priority} affect a thread receiving donations?
-It should do something sensible, but no particular behavior is
-required. None of the test cases call @func{thread_set_priority} from a
-thread while it is receiving a priority donation.
+It sets the thread's base priority. The thread's effective priority
+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!
@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.
+Yes. In general, your implementation may differ from the description,
+as long as its behavior is the same.
@end table
projects / pintos-anon / blobdiff