FQ-PIE Queue Discipline in the Linux Kernel: Design, Implementation and Challenges

NUMA multi-core systems divide system resources into several nodes. When an imbalance in the load between cores occurs, the kernel scheduler’s load balancing mechanism then migrates threads between cores or across NUMA nodes. Remote memory access is required for a thread to access memory on the previous node, which degrades performance. Threads to be migrated must be selected effectively and efficiently since the related operations run in the critical path of the kernel scheduler. This study focuses on improving inter-node load balancing for multithreaded applications. We propose a thread-aware selection policy that considers the distribution of threads on nodes for each thread group while migrating one thread for inter-node load balancing. The thread is selected for which its thread group has the least exclusive thread distribution, and thread members are distributed more evenly on nodes. This has less influence on data mapping and thread mapping for the thread group. We further devise several enhancements to eliminate superfluous evaluations for multithreaded processes, so the selection procedure is more efficient. The experimental results for the commonly used PARSEC 3.0 benchmark suite show that the modified Linux kernel with the proposed selection policy increases performance by 10.7% compared with the unmodified Linux kernel.

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HOW TO REPORT AND MONITOR THE PERFORMANCE OF WAITING LIST MANAGEMENT

International Journal of Technology Assessment in Health Care ◽

10.1017/s0266462302000442 ◽

2002 ◽

Vol 18 (3) ◽

pp. 611-618

Author(s):

Markus Torkki ◽

Miika Linna ◽

Seppo Seitsalo ◽

Pekka Paavolainen

Keyword(s):

Hallux Valgus ◽

Waiting Time ◽

Varicose Vein ◽

Elective Surgery ◽

Waiting Times ◽

Waiting List ◽

Mean Waiting Time ◽

Number Of Patients ◽

Potential Problems ◽

Queue Discipline

Objectives: Potential problems concerning waiting list management are often monitored using mean waiting times based on empirical samples. However, the appropriateness of mean waiting time as an indicator of access can be questioned if a waiting list is not managed well, e.g., if the queue discipline is violated. This study was performed to find out about the queue discipline in waiting lists for elective surgery to reveal potential discrepancies in waiting list management. Methods: There were 1,774 waiting list patients for hallux valgus or varicose vein surgery or sterilization. The waiting time distributions of patients receiving surgery and of patients still waiting for an operation are presented in column charts. The charts are compared with two model charts. One model chart presents a high queue discipline (first in—first out) and another a poor queue discipline (random) queue. Results: There were significant differences in waiting list management across hospitals and patient categories. Examples of a poor queue discipline were found in queues for hallux valgus and varicose vein operations. Conclusions: A routine waiting list reporting should be used to guarantee the quality of waiting list management and to pinpoint potential problems in access. It is important to monitor not only the number of patients in the waiting list but also the queue discipline and the balance between demand and supply of surgical services. The purpose for this type of reporting is to ensure that the priority setting made at health policy level also works in practise.

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Mini-ATX Computer System in Vehicle

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1115.484 ◽

2015 ◽

Vol 1115 ◽

pp. 484-487 ◽

Cited By ~ 1

Author(s):

Muhammad Sami ◽

Akram M. Zeki

Keyword(s):

Operating System ◽

Computer System ◽

Linux Kernel

The aim of this study is to create and assemble the system with customizing/building Linux kernel and environments to be compatible and efficient on mini-ITX computer. The objective of the study is to create/customizing lightweight operating system using GNU/Linux to be used on computer to be used on vehicle. The system would also optimize the size and functionalities most probably would be implemented on car computer system.Keywords: mini-ATX, CarPC, Linux, Ubuntu, Qt, QML

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Asymmetric software structures in the Linux kernel

Companion Proceedings of the 36th International Conference on Software Engineering - ICSE Companion 2014 ◽

10.1145/2591062.2591145 ◽

2014 ◽

Author(s):

Lei Wang ◽

Ping Wang ◽

Zhen Wang

Keyword(s):

Linux Kernel

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