Browsing by Subject "Operating systems"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Open Access
    Architectural Support for Optimizing Huge Page Selection Within the OS
    (2023-10-30) Manocha, A.; Yan, Z.; Tureci, E.; Aragón, J.L.; Nellans, D.; Martonosi, M.; Ingeniería y Tecnología de Computadores
    Irregular, memory-intensive applications often incur high translation lookaside buffer (TLB) miss rates that result in significant address translation overheads. Employing huge pages is an effective way to reduce these overheads, however in real systems the number of available huge pages can be limited when system memory is nearly full and/or fragmented. Thus, huge pages must be used selectively to back application memory. This work demonstrates that choosing memory regions that incur the most TLB misses for huge page promotion best reduces address translation overheads. We call these regions High reUse TLB-sensitive data (HUBs). Unlike prior work which relies on expensive per-page software counters to identify promotion regions, we propose new architectural support to identify these regions dynamically at application runtime. We propose a promotion candidate cache (PCC) that identifies HUB candidates based on hardware page table walks after a lastlevel TLB miss. This small, fixed-size structure tracks huge pagealigned regions (consisting of 𝑁 base pages), ranks them based on observed page table walk frequency, and only keeps the most frequently accessed ones. Evaluated on applications of various memory intensity, our approach successfully identifies application pages incurring the highest address translation overheads. Our approach demonstrates that with the help of a PCC, the OS only needs to promote 4% of the application footprint to achieve more than 75% of the peak achievable performance, yielding 1.19-1.33× speedups over 4KB base pages alone. In real systems where memory is typically fragmented, the PCC outperforms Linux’s page promotion policy by 14% (when 50% of total memory is fragmented) and 16% (when 90% of total memory is fragmented) respectively.
  • Thumbnail Image
    Publication
    Open Access
    Aula virtual basada en la Teoría constructivista empleada como apoyo para la enseñanza de los sistemas operativos a nivel universitario
    (Universidad de Murcia, Servicio de Publicaciones, 2008) Reyes Burgos, Karla Cecilia
    The present research proposes the design and implementation of a virtual classroom based on the constructivism theory, employed as a tool for the teaching of the operating systems course during the cycle 2006-1 at Universidad Católica Santo Toribio de Mogrovejo. This research also pushed us to know the characteristics that display the platforms of learning management, specially those used on this research (Moodle )and to take into value the performance of the virtual classroom on the visual ,navigability, contents and instruccional design aspects. The methodology used on this research was of descriptive type and it was used the systemic thinking technique for the organization of tasks. Finally, the performance of the virtual classroom was graded as very good concerning visual, navigability, contents and instruccional design aspects. It was recomended the use of virtual classrooms as a support in university and continuous formation courses