First complete draft.

diff --git a/ta-advice/HW3 b/ta-advice/HW3
index 6143c24bd7674465746be26aadadb19a9d7ad4f5..c0860c8e8d8211d57cc8d72a996647de094d14f7 100644 (file)
--- a/ta-advice/HW3
+++ b/ta-advice/HW3
@@ -61,8 +61,9 @@ A1:
 
 A2:
 
 
 A2:
 

-    The answer should describe code, not data; the data structures
-    have already been explained in A1.
+    The answer generally boils down to traversing the data structure
+    from A1.  The answer should describe code, not data; the data
+    structures have already been explained in A1.

 
 A3:
 
 
 A3:
 


@@ -113,8 +114,6 @@ A5:
     easier to find all the pages that belong to a given process (for
     cleanup when a process dies).
 
     easier to find all the pages that belong to a given process (for
     cleanup when a process dies).
 

-Check the submitted code, by hand, for the following: 
-

                       PAGING TO AND FROM DISK
                       =======================
 
                       PAGING TO AND FROM DISK
                       =======================
 


@@ -255,14 +254,16 @@ B8:
     Several possible answers:
 
        - Pre-lock all the pages that the system call will access,
     Several possible answers:
 
        - Pre-lock all the pages that the system call will access,

-          then unlock them when the system call completes.
+          then unlock them when the system call completes.  There must
+          be a discussion of how to avoid deadlock among processes
+          that, among them have all of the user pool locked, and want
+          more.

 
        - Page fault in kernel.
 
 
        - Page fault in kernel.
 

-       - Acquire a global lock needed to evict pages.  (But there
-          should be some additional explanation of how the system call
-          makes sure that those pages are in main memory in the first
-          place.)
+       - Acquire a global lock needed to evict pages.  There should
+          be some additional explanation of how the system call makes
+          sure that those pages are in main memory in the first place.

 
 B9:
 
 
 B9:
 


@@ -270,9 +271,8 @@ B9:
     to claim that the conditions for deadlock are "rare" or that the
     window in which deadlock can occur is "short" are not acceptable.
     In a proper design, deadlock is impossible, not just rare.  Deduct
     to claim that the conditions for deadlock are "rare" or that the
     window in which deadlock can occur is "short" are not acceptable.
     In a proper design, deadlock is impossible, not just rare.  Deduct

-    points.
-
-Check the submitted code, by hand, for the following:
+    points.  (This deduction is listed under B5 because similar claims
+    are common there.)

 
                         MEMORY MAPPED FILES
                         ===================
 
                         MEMORY MAPPED FILES
                         ===================


@@ -293,7 +293,7 @@ C2:
     For some reason, students sometimes talk about permanently
     assigning or pre-reserving memory mapped files to swap slots or to
     frames in physical memory here.  That's incorrect.  The assignment
     For some reason, students sometimes talk about permanently
     assigning or pre-reserving memory mapped files to swap slots or to
     frames in physical memory here.  That's incorrect.  The assignment

-    is explicit that mapping should be lazily loaded and written back
+    is explicit that mappings should be lazily loaded and written back

     to their files, not to swap.
 
 C3:
     to their files, not to swap.
 
 C3:

diff --git a/ta-advice/hw3.txt b/ta-advice/hw3.txt
new file mode 100644 (file)
index 0000000..48169d8
--- /dev/null
+++ b/ta-advice/hw3.txt
@@ -0,0 +1,113 @@
+HW3 DESIGN SUMMARY
+==================
+
+OVERALL
+
+  DOCUMENTATION
+    -20 Egregious violation of style versus design document example
+    -10 Numerous excessively long lines (> 79 characters)
+    -10 Numerous capitalization, punctuation, spelling, or grammar errors
+
+  DESIGN
+    -10 Failure to check return value of malloc()
+    -10 Use of ASSERT to check something that can actually fail, e.g. malloc()
+
+  CODING STYLE
+    -10 Inconsistent or bad coding style: no indentation, cramming
+        many statements into one line, other issues at TA's discretion
+    -10 Numerous very long source code lines (> 100 characters)
+    -10 Commented-out or #if'd out code makes real code hard to read
+    -10 Many missing comments on structure, structure members,
+        global or static variables, or function definitions
+    -10 Function(s) should be decomposed for clarity [indicate function]
+    -10 Cut-and-pasted code should be made into function [indicate where]
+    -10 Uninformative or deceptive identifiers
+
+  EXTRA CREDIT
+     +5 Sharing
+
+Subtotal: /10 (not capped)
+
+PROBLEM 1: PAGE TABLE MANAGEMENT
+
+  DOCUMENTATION
+    -25 Grossly inaccurate: documentation has no resemblance to code
+    -13 Important inaccuracies: documentation and code differ significantly
+        [indicate how]
+     -5 Minor inaccuracies: documentation and code differ [indicate how]
+     -5 A1: Missing entirely/missing comments or purpose/too long
+     -5 A2: Missing/non-responsive/too long/too short
+     -5 A3: Missing/non-responsive/too long/too short
+     -5 A3: Sharing implemented, but no explanation of how accessed
+        and dirty bits are coordinated
+     -5 A3: Sharing not implemented, but explanation states or implies
+        that a page can have multiple aliases
+     -5 A4: Missing/non-responsive/too long/too short
+     -5 A5: Missing/non-responsive/too long/too short
+
+  DESIGN
+    -30 Not implemented
+    -10 Page dirty status must be determined accurately, not approximately
+
+Subtotal: /25 (capped at 0)
+
+PROBLEM 2: PAGING TO AND FROM DISK
+
+  DOCUMENTATION
+    -45 Grossly inaccurate: documentation has no resemblance to code
+    -23 Important inaccuracies: documentation and code differ significantly
+        [indicate how]
+     -5 Minor inaccuracies: documentation and code differ [indicate how]
+     -5 B1: Missing entirely/missing comments or purpose/too long
+     -5 B2: Missing/non-responsive/too long/too short
+     -5 B3: Missing/non-responsive/too long/too short
+     -5 B4: Missing/non-responsive/too long/too short
+     -5 B4: Heuristic does not make sense
+     -2 B4: Claim that "struct intr_frame" is on user stack
+     -5 B5: Missing/non-responsive/too long/too short
+     -5 B5: Claim that deadlock is "rare" or has a "short" window
+     -5 B6: Missing/non-responsive/too long/too short
+     -3 B6: Didn't answer first part of question
+     -3 B6: Didn't answer second part of question
+     -3 B5: Disables interrupts
+     -5 B7: Missing/non-responsive/too long/too short
+     -5 B8: Missing/non-responsive/too long/too short
+     -3 B8: When pre-locking of pages is used, no discussion of
+        deadlock prevention
+     -3 B8: When global eviction lock is used, no discussion of
+        how pages are brought into main memory
+     -5 B9: Missing/non-responsive/too long/too short
+
+  DESIGN
+    -45 Not implemented
+     -5 Clock algorithm implementation literally uses a timer
+    -10 Clock algorithm implementation resets dirty bits
+     -5 Stack fault heuristic allows more than 32 bytes below stack pointer
+     -3 Stack limit is smaller than 1 MB
+
+Subtotal: /45 (capped at 0)
+
+PROBLEM 3: MEMORY-MAPPED FILES
+
+  DOCUMENTATION
+    -20 Grossly inaccurate: documentation has no resemblance to code
+    -10 Important inaccuracies: documentation and code differ significantly
+        [indicate how]
+     -5 Minor inaccuracies: documentation and code differ [indicate how]
+     -5 C1: Missing entirely/missing comments or purpose/too long
+     -5 C2: Missing/non-responsive/too long/too short
+     -5 C3: Missing/non-responsive/too long/too short
+     -2 C3: No mention of stack expansion
+     -2 C3: Claim that memory mappings in different processes can "overlap"
+     -5 C4: Missing/non-responsive/too long/too short
+
+  DESIGN
+    -20 Not implemented
+     -5 Pre-reserves or permanently assigning file pages to frames
+     -5 Pre-reserves or permanently assigning file pages to swap slots
+     -5 Global counter for mapid_t lacks synchronization
+     -5 Global table of file mappings lacks synchronization
+     -5 Global table allows multiple processes to access same file mapping
+     -5 Superfluous locking on per-thread data structure [which]
+
+Subtotal: /20 (capped at 0)