29set2025
10:30 Master's Defense By video conference
Topic on
Performance analysis and improvement proposals for the Linux kernel's Transparent Huge Pages
Student
Pedro Demarchi Gomes
Advisor / Teacher
Islene Calciolari Garcia
Brief summary
Most modern operating systems use huge pages to reduce address translation overhead in applications that use large amounts of memory. This work explores huge page management in different operating systems, presenting its benefits and challenges, such as memory bloat and memory fragmentation, which limit their efficient use. Therefore, this work proposes the Linux Reservation Based Huge Page System (LRBHPS), a reservation-based huge page management system to overcome these limitations, promoting more efficient allocation and reducing memory waste. LRBHPS is based on Linux and adopts a reservation strategy that creates a huge page only when there is a high probability of it being used, avoiding the mapping of huge pages that will not bring performance gains to the application. This is quite effective on systems with high memory fragmentation, where allocating contiguous 2 MB memory regions becomes difficult. The LRBHPS reservation system works by reserving a 2 MB memory region at the first page fault, mapping the huge page only after a certain number of base pages from the reservation have been used, when there is a greater probability that its use will actually benefit application performance. Furthermore, unpromoted reservations are destroyed after a predefined time if memory is under pressure, which contributes to more rational memory management and avoids waste. Another advancement presented by LRBHPS is the use of bulk zeroing, a technique that allows for more efficient page preparation. This method reduces the initialization time of huge pages and decreases system execution time. In performance tests with workloads such as Redis, GUPS, and Graphchi-PR, LRBHPS demonstrated efficiency in reducing system execution time and the number of cache misses, with significant gains in execution time and memory usage, even on highly fragmented systems. When comparing LRBHPS with Linux's Transparent Huge Pages (THP), it was found that LRBHPS is more flexible and adaptable, especially in environments where memory is highly fragmented. Its reservation-based approach makes it a promising alternative for reducing memory consumption and improving performance in large-scale systems.
Examination Board
Headlines:
| Islene Calciolari Garcia | IC / UNICAMP |
| Paulo Roberto Miranda Meirelles | IME / USP |
| Hervé Cédric Yviquel | IC / UNICAMP |
Substitutes:
| Edson Borin | IC / UNICAMP |
| Gustavo Maciel Dias Vieira | CCGT/UFSCar |