Consider a 32-bit computer with the following virtual memory architecture: - Each page is 2KB (211...

Transcribed Image Text:

Consider a 32-bit computer with the following virtual memory architecture: - Each page is 2KB (211 bytes). - Physical memory is 32 GB (2^35 bytes). Note: that is not mean 2^32 bytes. - Associated with each virtual page are 7 bits in the page table, including control and reserved bits. The exact nature of these bits is unimportant for this question. For completeness, they are: three bits controlled by the kernel (PTE_P, PTE_U, and PTE_W); 2 bits controlled by the hardware (Accessed and Dirty); and 2 bits reserved for the kernel (for example, PTE_COW). - The machine has a two-level page table structure analogous to the one used in JOS: each process has a page directory, each entry of which points to a page table. Each entry in the page directory has the same number of control and reserved bits as a page table entry: (1) What is the minimum number of bits in a second-level page table entry, and explain briefly. (2) What is the minimum number of bits in a page directory entry, and explain briefly. (3) Now assume that the entry size is rounded up to the nearest multiple of 4 bytes. Further assume that a page directory or page table must fit on a page. Programs on this machine use 32-bit quantities as instruction operands, but when the operand is an address, not all of these 32 bits are examined by the processor. How many address bits are actually used in this architecture? (4) How large is the per-process virtual memory space? Consider a 32-bit computer with the following virtual memory architecture: - Each page is 2KB (211 bytes). - Physical memory is 32 GB (2^35 bytes). Note: that is not mean 2^32 bytes. - Associated with each virtual page are 7 bits in the page table, including control and reserved bits. The exact nature of these bits is unimportant for this question. For completeness, they are: three bits controlled by the kernel (PTE_P, PTE_U, and PTE_W); 2 bits controlled by the hardware (Accessed and Dirty); and 2 bits reserved for the kernel (for example, PTE_COW). - The machine has a two-level page table structure analogous to the one used in JOS: each process has a page directory, each entry of which points to a page table. Each entry in the page directory has the same number of control and reserved bits as a page table entry: (1) What is the minimum number of bits in a second-level page table entry, and explain briefly. (2) What is the minimum number of bits in a page directory entry, and explain briefly. (3) Now assume that the entry size is rounded up to the nearest multiple of 4 bytes. Further assume that a page directory or page table must fit on a page. Programs on this machine use 32-bit quantities as instruction operands, but when the operand is an address, not all of these 32 bits are examined by the processor. How many address bits are actually used in this architecture? (4) How large is the per-process virtual memory space?

Answer rating: 100% (QA)

1 The minimum number of bits in a secondlevel page table entry is 7 since each entry in the page dir... View the full answer