linux里的Quick Fair Queueing Plus Scheduler
时间: 2024-10-24 10:17:47 浏览: 103
Linux内核中的快速公平队列(QFQ,Quick Fair Queuing)加调度器是一种用于网络接口卡(NICs)的调度策略,它结合了轮询(round-robin)和权重公平排队(WFQ)的优点[^1]。这种调度器旨在为不同的网络流量类别提供公平的服务,比如对带宽敏感的应用和服务质量优先(QoS)流量。
**QFQ工作原理**:
1. **轮询阶段**: 当数据包到达时,每个队列按顺序接收数据,就像传统的轮询一样。
2. **公平分配阶段**: 如果某个队列累积的数据包数量超过其预定的份额(由队列权重决定),这些超额的部分会平均分给其他队列,确保它们也得到公平的服务时间。
**示例配置**:
在sysctl配置文件中设置qfq相关参数,如限制每个类别的带宽和权重:
```bash
# 每个队列的带宽上限(以bps为单位)
net.core.default_qdisc=fq
net.ipv4.tcp_qdisc_default=fq
net.ipv4.tcp_fair_queue_default_burst=1000
net.ipv4.tcp_fair_queue_default_min_rate=100
# 设置队列权重
net.ipv4.tcp_fair_queue_default_weight=2 # 示例:第一个队列权重为2,第二个队列为1
```
相关问题
basic queueing theory
Queueing theory is a mathematical study of waiting lines or queues that arise in various real-life scenarios, such as customer service, traffic congestion, hospital emergency rooms, and telecommunications networks. Basic queueing theory involves the following concepts:
1. Arrival Process: This is the process of customers arriving at the queue. The arrival process can be modeled using different distributions, such as Poisson or exponential.
2. Service Process: This is the process of serving customers in the queue. The service process can also be modeled using different distributions, such as Poisson or exponential.
3. Queue Length: This is the number of customers waiting in the queue at any given time.
4. Queue Occupancy: This is the proportion of time that the server is busy serving customers.
5. System Capacity: This is the maximum number of customers that the system can handle at any given time.
6. Utilization: This is the proportion of time that the server is busy serving customers compared to the total time.
7. Waiting Time: This is the time that a customer spends waiting in the queue before being served.
8. Service Time: This is the time that a customer spends being served by the server.
9. Queueing Models: There are different queueing models that can be used to analyze queueing systems, such as the M/M/1 model, M/M/c model, M/G/1 model, and M/D/1 model.
10. Performance Measures: Different performance measures can be used to evaluate queueing systems, such as average waiting time, average queue length, and system throughput.
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