📝 Shared Pages in Paging of Operating System (68 MCQs)

📖 Explanation: Reentrant code is non-self-modifying and can be executed concurrently by multiple processes without interference. This property ensures that the shared code remains constant during execution. If the code were self-modifying, one process could alter instructions that another process is currently executing, leading to unpredictable behavior and system crashes. Dynamic linking and position-independent code are useful but not fundamental requirements for sharing pages.

📖 Explanation: Without sharing: 50 users × (200 KB code + 60 KB data) = 13,000 KB. With sharing: 200 KB code + 50 × 60 KB data = 3,200 KB. Saving = 13,000 - 3,200 = 9,800 KB. This demonstrates the significant memory savings achieved through page sharing, which is particularly important in time-sharing systems where many users run identical applications. The data portions remain private because each user has different document content and editing state.

📖 Explanation: If shared code is marked read-write, a bug or malicious process could modify the shared code. Since all processes share the same physical frames for that code, modifications would affect every process using that code. This could cause unpredictable behavior, crashes, or security vulnerabilities. The operating system must enforce read-only protection for shared pages through hardware protection bits. This scenario illustrates why protection mechanisms are crucial for system stability and security.

📖 Explanation: 28 KB / 4 KB per frame = 7 frames exactly (with no internal fragmentation). If the library were stored as 7 separate pages in logical memory, it would require exactly 7 physical frames in memory. The page table entries for each process would map their virtual pages for the library to these same 7 physical frames. This creates a one-to-one mapping that saves memory because only one copy exists in physical memory regardless of how many processes use the library.

📖 Explanation: Data pages contain process-specific state such as variables, stack contents, and heap allocations that vary between processes. Even if processes execute the same program, their data differs based on user input, program state, and execution history. Code pages are constant and therefore naturally sharable. Data sharing requires explicit synchronization mechanisms to maintain consistency, making it more complex than code sharing where processes only read from shared pages.

📖 Explanation: Shared code: 8 pages (one copy shared by all processes). Private data: 3 processes × 6 pages = 18 pages. Total = 8 + 18 = 26 frames. Without sharing, we would need 3 × (8 + 6) = 42 frames. The saving is 16 frames. This calculation demonstrates the efficiency of page sharing in multi-user environments. Note that the page table entries for each process would map their logical addresses for the shared code to the same physical frames, while mapping their data pages to different physical frames.

📖 Explanation: When shared code pages are swapped out, any process that needs to execute instructions from those pages will encounter page faults. The operating system must bring the pages back into memory to satisfy these faults. This situation demonstrates the importance of reference counting and careful memory management for shared pages. The operating system must track how many processes are using each shared page and only swap it out when no process is actively referencing it.

📖 Explanation: Self-modifying code modifies its own instructions during execution. If multiple processes share this code, modifications made by one process affect all other processes sharing the same physical pages. This violates the reentrancy requirement and leads to race conditions where process behavior depends on execution ordering. The system may crash or produce incorrect results. This is why self-modifying code is generally discouraged and operating systems enforce protection to prevent modifications to shared pages.

📖 Explanation: System libraries like the C standard library contain common functions used by many programs simultaneously. These libraries are compiled as reentrant code and can be shared across processes to save memory. User documents, session cookies, and configuration files contain process-specific data that cannot be shared without synchronization. Libraries such as libc, math libraries, and GUI frameworks are prime candidates for sharing because they are read-only and widely used.

📖 Explanation: Shared code: 50 MB (one copy). Private data: 100 users × 20 MB = 2,000 MB (2 GB). Total = 50 MB + 2,000 MB = 2,050 MB ≈ 2.5 GB. Without sharing: 100 × 70 MB = 7 GB. This exceeds the 4 GB physical memory, but with sharing, all 100 users can run simultaneously. This demonstrates the critical role of page sharing in enabling multi-user systems within memory constraints.

📖 Explanation: The valid-invalid bit indicates whether a page is part of the process's logical address space and thus legally accessible. For shared pages, this bit is set to valid for all processes sharing the page. If a process attempts to access a page that isn't in its address space (invalid bit set), the hardware traps to the operating system. This protection mechanism works identically for shared and non-shared pages. The OS manages this bit to define the boundaries of each process's logical address space.

📖 Explanation: The operating system marks shared pages as read-only to prevent writes that would affect other processes. While using reference counting to track usage, the primary consistency mechanism is write protection. If a process attempts to write to a shared page (which would be a bug if the code is truly reentrant), the hardware generates a page fault, allowing the OS to handle the violation. This protection ensures that shared pages remain consistent across all processes using them.

📖 Explanation: The page table maps virtual addresses to physical addresses independently for each process. Processes can map the same physical frames (shared code) to different virtual addresses in their respective logical address spaces. This flexibility is a key advantage of paging. For example, one process might map the shared library at virtual address 0x40000000 while another maps it at 0x50000000. The hardware handles translation through page tables, requiring no specific virtual address alignment between processes.

📖 Explanation: Shared pages allow processes to communicate by reading and writing to the same physical memory frames. This provides the fastest IPC mechanism because data is transferred in memory without any copying operations. Unlike pipes or message queues, shared memory avoids system call overhead for each data transfer. However, processes must implement their own synchronization mechanisms. The OS simply manages the page table mappings to share the physical pages between processes.

📖 Explanation: When the valid bit is 0, the page is not considered part of the process's logical address space. Any access attempt generates a trap to the operating system, typically resulting in a segmentation fault or page fault exception. The process cannot execute instructions from that virtual address. For shared code, this situation might occur if the OS hasn't properly set up the page table or if there was a bug in the process initialization code.

📖 Explanation: Shared code: 12 frames (one copy). Private data: 20 processes × 8 pages = 160 frames. Total = 12 + 160 = 172 frames. Without sharing: 20 × (12 + 8) = 400 frames. Saving = 228 frames. This demonstrates how sharing code significantly reduces memory usage, allowing many more processes to be active simultaneously. The OS manages the physical frames through the frame table, keeping track of which frames contain shared code.

📖 Explanation: Sharing introduces complexity in page table management. The OS must maintain reference counts to know when a shared page can be freed, ensure consistent mappings across processes, handle protection violations, and manage TLB entries for shared pages. While sharing reduces memory usage and improves multiprogramming, it requires additional OS data structures and careful coordination. The performance impact is typically small compared to the memory benefits, but the implementation complexity is higher than non-shared pages.

📖 Explanation: The TLB caches recent address translations, including those for shared pages. When a process accesses shared code, the virtual-to-physical address translation is cached in the TLB after the first access. This significantly speeds up subsequent accesses because the hardware can translate the address without consulting the page table in memory. The TLB operates identically for shared and non-shared pages, providing the same performance benefit. However, context switches may flush the TLB, requiring translations to be reloaded.

📖 Explanation: The OS maintains a reference count for each shared page. Every time a new process maps to the page, the count is incremented. When a process unmaps the page, the count is decremented. The page can only be freed when the reference count reaches zero, indicating no process is using it. This prevents premature freeing that would cause page faults for active processes. Reference counting is a standard technique in resource management to track shared resource usage.

📖 Explanation: Write permission on a shared page means either process can modify its contents. Since both processes expect their own private data but are actually sharing the same physical frame, writes from one process will overwrite data used by the other process. This leads to data corruption and unpredictable behavior. The OS must enforce read-only access for shared code pages. This example illustrates why protection is critical for sharing and why the OS must carefully manage page table permissions.

📖 Explanation: Shared pages significantly reduce disk I/O and memory usage. Instead of loading the same code from disk for each process (which would require multiple disk reads and memory allocation), the OS loads the code once into physical memory and maps it into multiple logical address spaces. This reduces disk access time, saves physical memory, and allows more processes to run concurrently. The time to create a new process is also reduced because shared code doesn't need to be loaded from disk.

📖 Explanation: 15 KB / 2 KB per page = 7.5 pages, so 8 pages are needed (rounded up). Total allocated space = 8 × 2 KB = 16 KB. Internal fragmentation = 16 KB - 15 KB = 1 KB. This shows that even shared pages incur internal fragmentation when the library size doesn't exactly match page boundaries. While page sharing saves memory compared to multiple copies, it doesn't eliminate the overhead of page-based allocation. This fragmentation is typically acceptable given the overall memory savings from sharing.

📖 Explanation: Reentrant code can be executed simultaneously by multiple processes because it doesn't modify itself during execution. This is essential for sharing because processes execute code interleaved in time on the CPU. If the code were self-modifying, one process's modifications could affect another's execution, causing errors. Reentrancy ensures the code behaves identically regardless of which process executes it, making it safe to share across processes. This property is fundamental to code sharing in paging systems.

📖 Explanation: Disabling page sharing would require loading separate copies of common programs for each user. This would dramatically increase memory usage, forcing the system to swap processes more frequently. Increased swapping would significantly degrade response times as processes wait for I/O operations. The system might be unable to support the same number of concurrent users. This illustrates why sharing is essential for time-sharing system performance and why modern operating systems rely heavily on shared pages.

📖 Explanation: Copy-on-write allows processes to share pages while maintaining the illusion of private memory. Initially, processes share a page with read-only permissions. When a process attempts to write, a page fault occurs, and the OS creates a private copy of the page for that process while leaving the original shared with others. This combines sharing benefits with private memory semantics. COW is widely used in process creation (fork() system call) where parent and child processes initially share pages until one writes to them.

📖 Explanation: When a context switch occurs, the TLB must be flushed (or ASID-based protection used) to prevent the new process from using address translations from the previous process. This happens regardless of whether pages are shared. Even though shared physical frames could be valid across processes, the virtual-to-physical mappings differ, and the TLB contains virtual addresses. Without ASIDs, flushing is necessary for correctness. This contributes to context-switch overhead but is an accepted cost of paging systems.

📖 Explanation: When shared libraries are mapped to the same virtual addresses across processes, the TLB entries remain valid across context switches because the translations are consistent. This improves TLB hit rates and reduces the overhead of context switching. Without ASIDs, this technique helps retain TLB entries. If virtual addresses differ, the TLB must be flushed more frequently. While memory usage remains the same, performance is enhanced by reducing translation misses.

📖 Explanation: The OS provides shared memory as a mechanism for sharing data pages across processes. This uses the same paging infrastructure that supports code sharing. Processes can map the same physical frames for data pages into their address spaces. However, unlike code sharing where pages are read-only, shared data pages require synchronization mechanisms (semaphores, mutexes) to prevent race conditions. This is a powerful IPC mechanism used in many applications for efficient data sharing.

📖 Explanation: Shared code must be read-only to prevent modifications that would affect other processes. This protection is enforced by the hardware through page table permission bits. If a process attempts to write to a read-only page, the hardware traps to the OS. This protection ensures shared code remains invariant. Execute permission is also typically set so processes can execute instructions from these pages. The combination is usually read-only and execute-only, not read-write.

📖 Explanation: Page sharing requires careful security management. While sharing can expose information if pages are incorrectly mapped between processes, the hardware protection bits prevent unauthorized writes. The OS must ensure that page tables are correctly configured and that processes cannot access pages they shouldn't. Shared libraries are safe because they contain no process-specific data. However, shared memory for IPC requires explicit permission and synchronization to maintain security and correctness.

📖 Explanation: The OS decrements the reference count for shared pages. Since other processes still use the shared code, the frames remain allocated. Only the process's private data frames are freed. The page table entries for the terminated process are removed. This demonstrates reference counting: pages remain until the last process using them terminates. This careful management ensures shared pages aren't prematurely freed while allowing proper cleanup when no processes need them.

📖 Explanation: Distributed shared memory (DSM) extends page sharing across multiple machines in a network. Pages can be shared by mapping them into the address spaces of processes on different computers. The system maintains consistency using protocols like invalidate or update-based approaches. Network file systems can also provide shared access to files but at a higher level than pages. DSM is complex due to network latency and consistency requirements but enables large-scale sharing across distributed systems.

📖 Explanation: Page tables handle different virtual-to-physical mappings independently. Process A's page table maps virtual 0x1000 to physical frame X, and Process B's maps virtual 0x2000 to the same physical frame X. The hardware uses each process's page table for address translation. This is perfectly valid and demonstrates the flexibility of paging. The virtual addresses don't need to match because the MMU performs translation. This independence is one of the key advantages of paging over segmentation.

📖 Explanation: Multiple applications use the same fonts in graphical environments. By storing font files as shared read-only pages, the OS loads them once into physical memory and maps them to all applications needing those fonts. This prevents redundant memory usage and reduces disk I/O. The technique is similar to shared libraries and demonstrates how sharing applies to various types of read-only data. It improves system performance, especially in environments with many graphical applications.

📖 Explanation: Shared pages are still subject to internal fragmentation because pages are allocated in fixed-size frames. If a shared library size doesn't match the page size, the last frame is partially filled regardless of sharing. However, the amount of wasted memory is the same whether the page is shared or private. The benefit of sharing is that this fragmentation occurs once per shared entity rather than once per process. Thus, sharing reduces the impact of internal fragmentation by amortizing it across all users.

📖 Explanation: Write permission on a shared page allows unauthorized modifications that affect all processes sharing the page. This could corrupt program behavior, crash applications, or be exploited to gain unauthorized access. A malicious process could modify shared library code to redirect execution to malicious routines. This is why the OS must strictly enforce protection bits. Such vulnerabilities highlight the critical importance of proper access control in shared page implementations.

📖 Explanation: ASIDs allow the TLB to hold entries from multiple processes simultaneously. When a context switch occurs, entries with the new process's ASID remain valid, while entries from other processes are distinguished by their ASIDs. This avoids flushing the TLB, improving performance in systems with frequent context switches. For shared pages, ASIDs can still distinguish between processes, but the physical frames are shared. This combined approach maintains TLB efficiency while supporting sharing.

📖 Explanation: With dynamic linking and versioning, shared libraries can be updated without restarting running processes. The library file is replaced on disk. New processes load the new version, while existing processes continue using the version they already have in memory (if reference counting prevents freeing). This demonstrates the flexibility of shared libraries and why version information is important. The OS must manage multiple versions simultaneously until all processes using the old version terminate.

📖 Explanation: Reentrant code is non-self-modifying and uses only local stack variables or read-only data. It can be safely interrupted and executed again before completion. Multiple processes can execute reentrant code interleaved without interference because each process maintains its own registers and stack. This property makes code sharable because the code itself remains constant while the execution state is maintained separately for each process. Reentrancy is essential for sharing code pages in multiprogrammed systems.

📖 Explanation: 35 KB / 8 KB = 4.375 pages, so 5 pages needed. Allocated = 5 × 8 KB = 40 KB. Wasted = 40 KB - 35 KB = 5 KB. This internal fragmentation occurs once for the shared library, not for each process. If this library were loaded separately for 100 processes, the waste would be 500 KB. Sharing reduces total fragmentation, demonstrating another benefit of page sharing. The cost of fragmentation is amortized across all processes using the library.

📖 Explanation: The OS generally does not track TLB contents because the TLB is a hardware-managed cache. The CPU hardware handles TLB lookups, misses, and replacements. The OS only sets up page tables; the hardware uses them to populate the TLB transparently. The OS may invalidate TLB entries when needed (e.g., during context switches or page table changes), but it doesn't know which entries are present at any given time. This separation of concerns keeps memory management efficient and hardware-independent.

📖 Explanation: Self-modifying code changes its own instructions during execution. If shared, modifications made by one process would change the code that other processes are executing. This violates the fundamental principle of sharing: that the shared resource should be invariant. Even if modification is intentional, the effects would be unpredictable and process-dependent. This is why shared libraries must be read-only and reentrant. Self-modifying code is rarely used today except in specific applications where code generation or optimization is needed.

📖 Explanation: Shared library: 12 frames. Private data A: 5 frames. Private data B: 7 frames. Total = 12 + 5 + 7 = 24 frames. This demonstrates how sharing reduces total memory usage. Without sharing: (12 + 5) + (12 + 7) = 36 frames. Saving = 12 frames. The frame table would show 12 frames marked as shared with reference count 2, while the remaining frames are allocated to specific processes. This efficient management allows more processes to run concurrently.

📖 Explanation: Shared memory pages can be used for inter-process communication when processes need to share and exchange data. Sensor data that multiple processes read is ideal because it's read-mostly and accessed frequently. Shared memory provides fast access without copying. However, processes must synchronize access to prevent races. Shared pages are less suitable for stack contents (process-private), source code (file-based rather than memory-based), or directory structures (kernel-managed).

📖 Explanation: In fork, the parent and child initially share pages with COW protection. Within a process, all threads share the address space, so COW semantics are consistent across threads. When one thread writes to a shared page after fork, the OS creates a private copy for that process (affecting all its threads). The implementation remains correct because threads share page tables. This demonstrates how page sharing mechanisms integrate with threading and COW to provide efficient process creation while maintaining memory isolation.

📖 Explanation: Each process still requires a full page table mapping its entire logical address space, including shared pages. The page table entries for shared pages point to the same physical frame numbers. While sharing doesn't reduce page table sizes, it reduces physical memory usage. The OS must store reference count information separately (in the frame table or auxiliary data structures). Therefore, sharing primarily saves physical frames, not page table space.

📖 Explanation: Two processes can share a writable page, typically for shared memory IPC, but must use synchronization mechanisms like semaphores or mutexes to prevent race conditions. Without coordination, writes from one process could interleave with writes from another, corrupting data. This is different from shared code, which is read-only. The OS allows writable shared pages when explicitly requested, but processes are responsible for ensuring correct access. This reflects the trade-off between performance and complexity in inter-process communication.

📖 Explanation: When a process terminates, the OS decrements the reference count of all pages it was using, including shared pages. If the count becomes 0, the shared page can be freed. If it's greater than 0, the page remains allocated. For example, a page shared by 5 processes has a count of 5. When one terminates, the count decreases to 4, and the page stays because other processes still need it. This reference counting is essential for proper memory management in sharing systems.

📖 Explanation: Page sharing typically doesn't affect boot time significantly. Shared pages are established as processes start and request memory mapping. The boot process itself involves loading the kernel and basic system services, which may have some shared components. However, most sharing occurs after boot when applications start. The impact on boot time is minimal compared to other boot activities like hardware initialization and filesystem mounting. The OS sharing infrastructure is initialized early but doesn't require extensive setup.

📖 Explanation: While sharing read-only code pages is generally beneficial, there are trade-offs. The OS must manage reference counts, ensure TLB consistency, and handle protection correctly. Sharing also requires careful virtual memory management. In some cases, the overhead of managing shared pages might outweigh the memory benefits, especially for small code segments or systems with limited multiprogramming. Additionally, some systems may prioritize isolation over sharing for security or simplicity reasons.

📖 Explanation: In most systems, when a process attempts to modify a shared page (especially after fork), the OS uses copy-on-write. The parent receives a private copy of the page, and the modification affects only the parent. The original shared page remains unchanged and continues to be shared with the child. This ensures that modifications don't affect other processes while maintaining sharing for unmodified pages. This is a key optimization in modern operating systems.

📖 Explanation: When system libraries are implemented as shared pages, they can be updated on disk without affecting currently running processes that are using old versions in memory. New processes will load the updated version. This allows system maintenance without restarting applications. Additionally, sharing saves memory and improves cache locality. The versioning mechanism ensures processes continue using the version they were compiled with. This flexibility is a major advantage of dynamic linking with shared libraries.

📖 Explanation: Embedded systems often have limited RAM but can use shared pages to run multiple applications from the same code stored in flash or ROM. This reduces RAM usage by loading code once and mapping it to multiple processes. This is especially useful in systems with many similar tasks. The memory savings allow more applications to run simultaneously or reduce hardware costs. Page sharing is thus a critical technique for resource-constrained embedded systems.

📖 Explanation: Without page sharing, the OS would load a separate copy of the editor's code for each user. For 100 users, if the editor is 50 KB, memory usage would be 100 × 50 KB = 5 MB just for code. With sharing, only 50 KB is needed. This demonstrates why sharing is essential for multi-user systems. The increased memory usage would likely cause the system to page heavily or be unable to support many users. This illustrates the importance of sharing in enabling efficient multi-user environments.

📖 Explanation: GUI environments benefit significantly from shared pages because many applications use the same system libraries for window management, font rendering, and graphics. These libraries are read-only and can be shared, reducing memory usage. In contrast, database caches, user sessions, and configurations contain process-specific data that cannot be shared. This scenario illustrates how sharing applies to common read-only resources that many processes need simultaneously.

📖 Explanation: When only a few processes use shared memory, the overhead of setting up and managing shared pages (creating mappings, handling synchronization, reference counting) may not be justified. For example, with only two processes, copying data between them might be simpler and more maintainable than complex shared memory management. The memory savings are minimal, but implementation complexity increases. This trade-off explains why sharing isn't universally beneficial and must be evaluated based on system conditions.

📖 Explanation: Even with 64-bit virtual address spaces, physical memory remains a finite resource. Page sharing still saves physical memory, allowing more pages to be cached or more processes to run. While virtual address space is abundant, physical memory capacity is limited by hardware cost and technology. Sharing remains important for performance and efficiency regardless of address space size. The virtual address space size doesn't affect the need to conserve physical memory through sharing.

📖 Explanation: Page sharing and segmentation can coexist. In systems that support both, shared pages may still be used within segments. The global descriptor table (GDT) defines segment boundaries and protection, while paging provides page-level sharing. These are orthogonal memory management techniques. Programs can share code across processes at the page level while still using segments for protection and organization. This combination is used in systems like x86 where segmentation and paging both exist.

📖 Explanation: A hardware error corrupting a shared page would affect all processes using that page because they share the same physical frame. This could cause data corruption, crashes, or incorrect behavior in multiple applications simultaneously. Without ECC (Error Correcting Code) memory, the corruption would propagate to all users of the shared code. This demonstrates a disadvantage of sharing: errors in shared resources have a broad impact compared to private pages where only one process is affected. High-availability systems often use ECC memory to mitigate this risk.

📖 Explanation: To prevent information leaks, shared pages should be immutable (read-only). Writable shared pages could be used to leak information between processes if not properly synchronized. Many secure systems restrict sharing to read-only code and data, requiring explicit permission and careful synchronization for writable shared memory. This approach minimizes the attack surface while still providing memory efficiency benefits. The OS must enforce strict protection and validate any sharing requests to maintain security.

📖 Explanation: When a shared library is updated with minor changes (same major version number), existing processes continue using the version they already have loaded in memory. New processes will load the updated version. This allows system updates without disrupting running applications. The OS maintains multiple copies of the library in memory (one for each version in use). This demonstrates the versioning mechanism that makes shared libraries practical for system maintenance.

📖 Explanation: When shared pages are used, the OS loads the shared code once from disk. Subsequent processes mapping the same code don't need additional disk I/O because the code is already in memory. This significantly reduces disk reads, improving application loading times. This is particularly beneficial for frequently used libraries and applications. The initial loading cost is amortized across all processes using the shared code, making system operation more efficient overall.

📖 Explanation: A memory leak in a shared library would affect all processes using it because the leaked memory isn't reclaimed while any process holds a reference. This could cause gradual memory depletion across the entire system as more processes use the library. In contrast, a leak in private code only affects that specific process and is cleaned up when the process terminates. This illustrates that bugs in shared code can have broader system impact, emphasizing the importance of careful resource management in shared libraries.

📖 Explanation: With very few processes, the memory savings from sharing are minimal (e.g., saving 1 MB of code for 2 processes). However, the overhead includes maintaining reference counts, managing shared page tables, ensuring consistency, and handling protection. This overhead might outweigh the savings, making sharing less beneficial. In such cases, simpler memory management without sharing might be more efficient. This illustrates that memory management techniques should be evaluated in context, not always applied universally.

📖 Explanation: Global variables in libraries typically represent shared state that would be inconsistent if multiple processes share the same physical pages. Each process expects its own copy of global data. This is why library code is separated from library data. The code is shared (read-only), while data pages are private to each process. If a library uses global variables, these must be in private data pages. This architectural separation is essential for correct sharing.

📖 Explanation: Shared pages can reduce reliability because a bug in shared code affects all processes using it, rather than just one process. Similarly, a security vulnerability in a shared library exposes all processes to that risk. This is a disadvantage of sharing. However, thorough testing of shared code benefits all users, potentially improving reliability. This trade-off between efficiency and fault isolation is a fundamental consideration in system design. Protected execution environments and robust testing help mitigate these risks.

📖 Explanation: Real-time systems require predictable execution times. Page sharing can introduce variability through shared page access patterns, TLB effects, and reference count management. Additionally, page faults or TLB misses in shared pages might affect timing more unpredictably. To maintain deterministic behavior, real-time systems may prefer private memory mappings or avoid sharing. This illustrates how system requirements influence memory management strategy selection.

📖 Explanation: Shared pages can improve cache utilization because frequently used code is stored in one physical location. When multiple processes use shared code, the cache lines holding that code benefit from temporal locality across processes. This increases cache hit rates and improves performance. However, if processes with different access patterns share pages, it could cause cache conflicts. Overall, well-designed shared page usage generally enhances cache efficiency through code reuse.