-@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.
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
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
@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,
Priority donation only changes the priority of the donee
thread. The donor thread's priority is unchanged.
-Priority donation is not additive: if thread @var{A} (with priority 3) donates
-to thread @var{B} (with priority 5), then @var{B}'s new priority is 3, not 8.
+Priority donation is not additive: if thread @var{A} (with priority 5) donates
+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?
@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