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

[pintos-anon] / doc / vm.texi

diff --git a/doc/vm.texi b/doc/vm.texi
index 6e5d5a076b281bdb6dd72515e9b2c22b792fbf93..e6ff141067f58ce2b80cbb2f2a807a018267519d 100644 (file)
--- a/doc/vm.texi
+++ b/doc/vm.texi
@@ -316,11 +316,12 @@ Some way of translating in software from virtual page frames to
 physical page frames.  Pintos provides a hash table that you may find
 useful for this purpose (@pxref{Hash Table}).
 
 physical page frames.  Pintos provides a hash table that you may find
 useful for this purpose (@pxref{Hash Table}).
 

-It is possible to do this translation without adding a new data
-structure, by modifying the code in @file{userprog/pagedir.c}.  However,
-if you do that you'll need to carefully study and understand section 3.7
-in @bibref{IA32-v3}, and in practice it is probably easier to add a new
-data structure.
+You don't strictly need a new data structure for this.  You could
+instead modify the code in @file{userprog/pagedir.c}.  If you do that
+you'll need to thoroughly understand how 80@var{x}86 page tables work
+by, e.g.,@: studying section 3.7, ``Page Translation Using 32-Bit
+Physical Addressing,'' in @bibref{IA32-v3a}.  In practice, most groups
+use a separate data structure.

 
 @item
 Some way of finding a page on disk (in a file or in swap) if it is not
 
 @item
 Some way of finding a page on disk (in a file or in swap) if it is not


@@ -419,11 +420,10 @@ Bits}) to implement an approximation to LRU.  Your algorithm should
 perform at least as well as the ``second chance'' or ``clock''
 algorithm.
 
 perform at least as well as the ``second chance'' or ``clock''
 algorithm.
 

-Your design should allow for parallelism.  Multiple processes should
-be able to process page faults at once.  If one page fault require
+Your design should allow for parallelism.  If one page fault requires

 I/O, in the meantime processes that do not fault should continue
 I/O, in the meantime processes that do not fault should continue

-executing and other page faults that do not require I/O should be able to
-complete.  These criteria require some synchronization effort.
+executing and other page faults that do not require I/O should be able
+to complete.  These criteria require some synchronization effort.

 
 @node Lazy Loading
 @subsection Lazy Loading
 
 @node Lazy Loading
 @subsection Lazy Loading


@@ -440,25 +440,25 @@ be written to swap.
 
 The core of the program loader is the loop in @func{load_segment} in
 @file{userprog/process.c}.
 
 The core of the program loader is the loop in @func{load_segment} in
 @file{userprog/process.c}.

-Each time around the loop, @code{read_bytes} receives the number of
-bytes to read from the executable file and @code{zero_bytes} receives
+Each time around the loop, @code{page_read_bytes} receives the number of
+bytes to read from the executable file and @code{page_zero_bytes} receives

 the number of bytes to initialize to zero following the bytes read.  The
 two always sum to @code{PGSIZE} (4,096).  The handling of a page depends
 on these variables' values:
 
 @itemize @bullet
 @item
 the number of bytes to initialize to zero following the bytes read.  The
 two always sum to @code{PGSIZE} (4,096).  The handling of a page depends
 on these variables' values:
 
 @itemize @bullet
 @item

-If @code{read_bytes} equals @code{PGSIZE}, the page should be demand
+If @code{page_read_bytes} equals @code{PGSIZE}, the page should be demand

 paged from disk on its first access.
 
 @item
 paged from disk on its first access.
 
 @item

-If @code{zero_bytes} equals @code{PGSIZE}, the page does not need to
+If @code{page_zero_bytes} equals @code{PGSIZE}, the page does not need to

 be read from disk at all because it is all zeroes.  You should handle
 such pages by creating a new page consisting of all zeroes at the
 first page fault.
 
 @item
 be read from disk at all because it is all zeroes.  You should handle
 such pages by creating a new page consisting of all zeroes at the
 first page fault.
 
 @item

-If neither @code{read_bytes} nor @code{zero_bytes} equals
+If neither @code{page_read_bytes} nor @code{page_zero_bytes} equals

 @code{PGSIZE}, then part of the page is to be read from disk and the
 remainder zeroed.  This is a special case.  You are allowed to handle
 it by reading the partial page from disk at executable load time and
 @code{PGSIZE}, then part of the page is to be read from disk and the
 remainder zeroed.  This is a special case.  You are allowed to handle
 it by reading the partial page from disk at executable load time and


@@ -669,7 +669,7 @@ kernel functions need to obtain memory.
 You can layer some other allocator on top of @func{palloc_get_page} if
 you like, but it should be the underlying mechanism.
 
 You can layer some other allocator on top of @func{palloc_get_page} if
 you like, but it should be the underlying mechanism.
 

-Also, you can use the @option{-u} option to @command{pintos} to limit
+Also, you can use the @option{-ul} option to @command{pintos} to limit

 the size of the user pool, which makes it easy to test your VM
 implementation with various user memory sizes.
 
 the size of the user pool, which makes it easy to test your VM
 implementation with various user memory sizes.
 


@@ -712,7 +712,7 @@ with the file mapped into your address space, you can directly address
 it like so:
 
 @example
 it like so:
 
 @example

-write (addr, 64, STDOUT_FILENO);
+write (STDOUT_FILENO, addr, 64);

 @end example
 
 Similarly, if you wanted to replace the first byte of the file,
 @end example
 
 Similarly, if you wanted to replace the first byte of the file,