Operating Systems
Process Concepts and Cpu Scheduling
Marks 1Marks 2
Synchronization and Concurrency
Marks 1Marks 2
Memory Management
Marks 1Marks 2Marks 5
File System IO and Protection
Marks 1Marks 2Marks 5
1
GATE CSE 2003
MCQ (Single Correct Answer)
+2
-0.6
A processor uses $$2$$-level page tables for virtual to physical address translation. Page tables for both levels are stored in the main memory. Virtual and physical addresses are both $$32$$ bits wide. The memory is byte addressable. For virtual to physical address translation, the $$10$$ most significant bits of the virtual address are used as index into the first level page table while the next $$10$$ bits are used as index into the second level page table. The $$12$$ least significant bits of the virtual address are used as offset within thepage. Assume that the page table entries in both levels of page tables are $$4$$ bytes wide. Further, the processor has a translation look-aside buffer (TLB), with a hit rate of $$96$$%. The TLB caches recently used virtual page numbers and the corresponding physical page numbers. The processor also has a physically addressed cache with a hit rate of $$90$$%. Main memory access time is $$10$$ ns, cache access time is $$1$$ ns, and TLB access time is also $$1$$ ns.

Suppose a process has only the following pages in its virtual address space: two contiguous code pages starting at virtual address $$0 \times 00000000,$$ two contiguous data pages starting at virtual address $$0 \times 00400000,$$ and a stack page starting at virtual address $$0 \times FFFFF000.$$ The amount of memory required for storing the page tables of this process is

A
$$8$$ KB
B
$$12$$ KB
C
$$16$$ KB
D
$$20$$ KB
2
GATE CSE 2003
MCQ (Single Correct Answer)
+2
-0.6
A processor uses $$2$$-level page tables for virtual to physical address translation. Page tables for both levels are stored in the main memory. Virtual and physical addresses are both $$32$$ bits wide. The memory is byte addressable. For virtual to physical address translation, the $$10$$ most significant bits of the virtual address are used as index into the first level page table while the next $$10$$ bits are used as index into the second level page table. The $$12$$ least significant bits of the virtual address are used as offset within thepage. Assume that the page table entries in both levels of page tables are $$4$$ bytes wide. Further, the processor has a translation look-aside buffer (TLB), with a hit rate of $$96$$%. The TLB caches recently used virtual page numbers and the corresponding physical page numbers. The processor also has a physically addressed cache with a hit rate of $$90$$%. Main memory access time is $$10$$ ns, cache access time is $$1$$ ns, and TLB access time is also $$1$$ ns.

Assuming that no page faults occur, the average time taken to access a virtual address is approximately (to the nearest $$0.5$$ ns)

A
$$1.5$$ ns
B
$$2$$ ns
C
$$3$$ ns
D
$$4$$ ns
3
GATE CSE 2002
MCQ (Single Correct Answer)
+2
-0.6
Dynamic linking can cause security concerns because
A
Security is dynamic
B
The path for searching dynamic libraries is not known till runtime
C
Linking is insecure
D
Cryptographic procedures are not available for dynamic linking
4
GATE CSE 2001
MCQ (Single Correct Answer)
+2
-0.6
Consider a machine with 64 MB physical memory and a 32-bit virtual address space. If the page size is 4KB, what is the approximate size of the page table?
A
16 M
B
8 MB
C
2 MB
D
24 MB
GATE CSE Subjects
Theory of Computation
Operating Systems
Algorithms
Digital Logic
Database Management System
Data Structures
Computer Networks
Software Engineering
Compiler Design
Web Technologies
General Aptitude
Discrete Mathematics
Programming Languages
Computer Organization