六分页式虚存中的一些实现问题.PDF

六、分页式虚存中的一些实现问题 When ... Process creation determine program size create page table Copy-on-Write Copy-on-Write (COW) allows both parent and child processes Memory-Mapped Files to initially share the same pages in memory. If either process modifies a shared page, only then is the page copied Process switching MMU reset for new process TLB flushed Page fault determine virtual address causing fault swap target page out, needed page in Process termination release page table, pages 1. Page Fault 的处理 instruction -- trap a) Hardware traps to kernel instruction -- fault b) General registers saved instruction -- interrupt c) OS determines which virtual page needed instruction -- exception d) OS checks validity of address, seeks page frame instruction e) If selected frame is dirty, write it to disk f) OS brings schedules new page in from disk g) Page tables updated h) Faulting instruction backed up to when it began i) Faulting process scheduled j) Registers restored k) Program continues 2. 指令备份 例如： 如下语句发生 page fault case 1