• Due Date: March 23, 2022

• Binhao Qin (bhqin)
• Gil Dhason (adhason)
• Weili Li (weilirs)

• Determine state-diagram for page life cycle (swap-backed and file-backed) (Thursday, Mar. 10-11)

• State diagram check (OH or lab) (Thursday, Mar. 10, 2:30 p.m or Friday)

• Functionality (life cycle) testing (Sunday, Mar. 13) (in parallel)

• Determine class abstraction and data structure (Sunday, Mar. 13)

• Implementation of basic features (Wednesday, Mar. 16)

• Regressive testing (Sunday, Mar. 20) (in parallel)

• Implementation of eviction, optimization, ... (Sunday, Mar. 20)

• More testing (Wednesday, Mar. 23) (in parallel)

• Wrapping up (Wednesday, Mar. 23)

Link to Online Document

stateDiagram-v2
    [*] --> mapped_disk: vm_map
    mapped_disk --> mapped_clean_physmem: read
    mapped_disk --> mapped_dirty_physmem: write
    mapped_clean_physmem --> mapped_dirty_physmem: write
    mapped_dirty_physmem --> mapped_dirty_physmem: read || write || (clock && !swept)
    mapped_clean_physmem --> mapped_clean_physmem: read || (clock && !swept)
    mapped_clean_physmem --> mapped_clean_not_ref: clock && swept && !evict
    mapped_clean_not_ref --> mapped_clean_physmem: read
    mapped_clean_not_ref --> mapped_dirty_physmem: write
    mapped_dirty_physmem --> mapped_disk: clock && evict (copy)
    mapped_clean_physmem --> mapped_disk: clock && evict
    mapped_dirty_physmem --> mapped_dirty_not_ref: clock && swept && !evict
    mapped_dirty_not_ref --> mapped_dirty_physmem: read || write
    mapped_clean_not_ref --> mapped_disk: clock && evict
    mapped_clean_not_ref -->  mapped_clean_not_ref: clock && !evict
    mapped_dirty_not_ref --> mapped_disk: clock && evict (copy)
    mapped_dirty_not_ref --> mapped_dirty_not_ref: clock && !evict

    note right of mapped_clean_physmem
        valid: true
        resident: true
        dirty: false
        referenced: true
        r_enable: true
        w_enable: false
    end note

    note right of mapped_dirty_physmem
        valid: true
        resident: true
        dirty: true
        referenced: true
        r_enable: true
        w_enable: true
    end note

    note right of mapped_disk
        valid: true
        resident: false
        dirty: false
        referenced: false
        r_enable: false
        w_enable: false
    end note

    note right of mapped_clean_not_ref
        valid: true
        resident: true
        dirty: false
        referenced: false
        r_enable: false
        w_enable: false
    end note

    note right of mapped_dirty_not_ref
        valid: true
        resident: true
        dirty: true
        referenced: false
        r_enable: false
        w_enable: false
    end note

• DiskBlock: Data structure with file name and block number, implements hash.

• Page: Abstraction of a physical page, only fixed amount of presistent instances in pager. Contains metadata.

  • Need to be careful to update referer pointer whenever disk pointer is updated.
  • Call broadcast after shared state changes

• AddressSpace: Abstraction of a virtual address space. Implements virtual pointer, and syntax sugar of Entry.

  • valid and resident bits are not needed, therefore removed, only pointers of DiskBlock remain

• Allocator: Simple class for managing resources such as swap block and physical page.

• Clock: Implementation of clock algorithm, uses unordered_map and list for O(1) time complexity and O(n) memory

• Pager: Singleton class. A pager contains many tables for different associations and manages these association and invariants.

• There is only one physical instance of DiskBlock

• Referer pointer and disk pointer must be synchronize

• A non-resident page must have zero ppn and null disk and referer pointer

• Having non-null disk and referer pointer with zero ppn indicates a swap-backed page in zero-page

• Zero page is never evicted

1. Add header files under include and add source files under src.

2. Run make syntax before adding and commiting code and fix any error.

3. Use git add -u and git add <file>, don't do git add ..

4. Don't commit configuration files, temp files and build files. You can use .gitignore to prevent this.

5. Do a git pull or git pull --rebase before pushing.