-Design (/120 points)
---------------------
+Test cases [[/25]]
+------------------
+ -15 Didn't write own test cases
+ -10 Insufficient testing
-a) DESIGNDOC (/60 pts)
- a) Arg passing (/10)
- b) System calls (/20)
- Didn't discuss global vs local allocation of fileID's
- How to handle exceptions & why (ie killing processes
- that do bad things)
- Explaining choice of openFileID's & ASIDS
- c) Multiprogramming (/30)
- How to find a free page.
- Explaining how new processes are executed.
- How they deal with running out of memory error on loading.
+Design [[/100]]
+---------------
-b) Other Design (/60 pts)
+Quality of DESIGNDOC
+ -10 Arg passing
+ -20 Copying data around:
+ User-to-kernel copying.
+ Kernel-to-user copying.
+ String copying.
+ -20 System calls:
+ Allocation of file descriptors.
+ Handling exceptions and related cleanup.
+ pid_t rationale (if they changed tid_t -> pid_t mapping).
+ Synchronization of system calls and filesystem.
- 1. Argument passing
- No checking for page boundaries in argument passing -10
- Uses memcpy/bcopy/memmove or file reading/writing for +5
- copying up to/starting from page boundaries -- good job!
- (Search for memcpy/bcopy, not just extern, make sure they call it
- with the possibility of copying more than 4 bytes at a time. ALSO if
- they do File Read/Writes then that is not byte-by-byte but they will
- fail page crossing only take off for failing the pagecrossing test.)
- Don't decomp / reuse translation code -5
- Using strtok instead of strtok_r or strsep -1
- (strtok is not thread-safe)
+Overall:
+ -1 Gratuitous use of malloc() (e.g. for allocating a list or a lock)
+ -1 Inappropriate use of ASSERT (e.g. to verify that malloc() succeeded)
- 2. System calls
- No checking for page boundaries in system calls -20
- (-5 if they only forgot for some system calls but did it somewhere)
- Interrupts turned off for all system calls -10
- Doesn't close open files after process exits -2
- table/when file is closed, it is not removed from file table
- Uses printf/fscanf/putc/getc when interacting -5
- with StandardInput / StandardOutput
- Using fixed length buffer for Read/Write -5
- Using pointer to int casts as ASID/FileId without justifying -5
+Program arguments:
+ +1 Support multiple pages of arguments.
- 3. Multiprogramming
- Don't use the bitmap object -5
- Bitmap is not cleared when process dies -5
- Access to bitmap is not sychronized -5
- getting next ASID is not synchronized -5
- ...or (mututally exclusive, depending on their solution)...
- Doesn't use ASID's at all, but their system for identifying -5
- processes has synchronization or uniqueness problems (e.g.
- careless use of AddrSpace*'s)
- Multiple translations for a page -10
- (One vaddr maps to two paddr's, or vice versa)
+User/kernel copying:
+ -5 Too many copies of user/kernel copying code
+ -20 Doesn't check for page boundaries
+ -10 Imperfect checking for page boundaries
+ -5 Doesn't check whether pointers are at or above PHYS_BASE
+ -2 Imperfect checking whether pointers are at or above PHYS_BASE
+ +3 Copies large chunks while properly observing page boundaries
+ +3 Scans for string null terminators w/o checking individual bytes
+ while properly observing page boundaries
+ +3 Uses get_user() and put_user() functions from FAQ for copying
-Style (/30 points)
-------------------
-0) Had to modify code to get to compile the first -10
- time
-1) Minor changes to machine code -10
-2) Extraneous output -5
-3) Unexplained dependencies -5
-4) Not Decomposing Exception handler -5
+System call design:
+ -5 Disables interrupts without reasonable justification
+ -2 Doesn't close open files at process exit
+ -2 Doesn't acquire file system lock to close files at process exit
+ -5 Buffer overflow in read or write system call
+ -5 System call error exit leaks memory/fails to release global lock
+ -5 Uses a pointer as a file descriptor or pid without justifying
+
+Style [[/25]]
+-------------
+ -5 Extraneous output caused warnings
+ -5 Didn't print process termination messages
+ -5 One big function for handling system calls
+ -5 No attempt to conform to existing coding style
-TESTCASEs (/30 points)
-----------------------
- Don't write own testcases -15
- Not sufficient testing up to -10
+Comments
+--------
projects / pintos-anon / blobdiff