OSTEP-MLFQ(多级反馈队列)-HOMEWORK(simulation)

最新推荐文章于 2025-11-30 16:29:01 发布

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最新推荐文章于 2025-11-30 16:29:01 发布 · 403 阅读

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#操作系统

本文探讨了如何使用模拟器来实现和分析多级反馈队列（MLFQ）调度器。通过调整参数，模拟RR调度器，以及研究如何通过特定工作负载使一个任务在特定时间内获得99%的CPU资源。还讨论了如何保证长时间运行的任务至少获得5%的CPU，并分析了在不同I/O处理策略下对队列的影响。

1. Run a few randomly-generated problems with just two jobs and

two queues; compute the MLFQ execution trace for each. Make

your life easier by limiting the length of each job and turning off

I/Os.

运行一些随机产生的问题（？）：两个job，两个队列，限制每个job的长度，不进行io，计算mlfq的运行轨迹

andy@LAPTOP-B6LCN2OM:~/HW-MLFQ$ ./mlfq.py -j 2 -n 2 -m 5 -M 0 -c
Here is the list of inputs:
OPTIONS jobs 2
OPTIONS queues 2
OPTIONS allotments for queue  1 is   1
OPTIONS quantum length for queue  1 is  10
OPTIONS allotments for queue  0 is   1
OPTIONS quantum length for queue  0 is  10
OPTIONS boost 0
OPTIONS ioTime 5
OPTIONS stayAfterIO False
OPTIONS iobump False


For each job, three defining characteristics are given:
  startTime : at what time does the job enter the system
  runTime   : the total CPU time needed by the job to finish
  ioFreq    : every ioFreq time units, the job issues an I/O
              (the I/O takes ioTime units to complete)

Job List:
  Job  0: startTime   0 - runTime   4 - ioFreq   0
  Job  1: startTime   0 - runTime   2 - ioFreq   0


Execution Trace:

[ time 0 ] JOB BEGINS by JOB 0
[ time 0 ] JOB BEGINS by JOB 1
[ time 0 ] Run JOB 0 at PRIORITY 1 [ TICKS 9 ALLOT 1 TIME 3 (of 4) ]
[ time 1 ] Run JOB 0 at PRIORITY 1 [ TICKS 8 ALLOT 1 TIME 2 (of 4) ]
[ time 2 ] Run JOB 0 at PRIORITY 1 [ TICKS 7 ALLOT 1 TIME 1 (of 4) ]
[ time 3 ] Run JOB 0 at PRIORITY 1 [ TICKS 6 ALLOT 1 TIME 0 (of 4) ]
[ time 4 ] FINISHED JOB 0
[ time 4 ] Run JOB 1 at PRIORITY 1 [ TICKS 9 ALLOT 1 TIME 1 (of 2) ]
[ time 5 ] Run JOB 1 at PRIORITY 1 [ TICKS 8 ALLOT 1 TIME 0 (of 2) ]
[ time 6 ] FINISHED JOB 1

Final statistics:
  Job  0: startTime   0 - response   0 - turnaround   4
  Job  1: startTime   0 - response   4 - turnaround   6

  Avg  1: startTime n/a - response 2.00 - turnaround 5.00

2. How would you run the scheduler to reproduce each of the examples in the chapter?

如何使用这个模拟器复现书中的一些例子？

简单起见，这里选择的是书中第一个例子：

如图：一个job，三级队列，0时进入，耗时200（为了答案比较简单，这里设置运行时间为10），不进行io

其中-a选项规定了每个队列的分配时间为1，-q选项规定了每个队列的时间片大小为1

andy@LAPTOP-B6LCN2OM:~/HW-MLFQ$ ./mlfq.py -l 0,10,0 -c -a 1 -q 1
Here is the list of inputs:
OPTIONS jobs 1
OPTIONS queues 3
OPTIONS allotments for queue  2 is   1
OPTIONS quantum length for queue  2 is   1
OPTIONS allotments for queue  1 is   1
OPTIONS quantum length for queue  1 is   1
OPTIONS allotments for queue  0 is   1
OPTIONS quantum length for queue  0 is   1
OPTIONS boost 0
OPTIONS ioTime 5
OPTIONS stayAfterIO False
OPTIONS iobump False


For each job, three defining characteristics are given:
  startTime : at what time does the job enter the system
  runTime   : the total CPU time needed by the job to finish
  ioFreq    : every ioFreq time units, the job issues an I/O
              (the I/O takes ioTime units to complete)

Job List:
  Job  0: startTime   0 - runTime  10 - ioFreq   0


Execution Trace:

[ time 0 ] JOB BEGINS by JOB 0
[ time 0 ] Run JOB 0 at PRIORITY 2 [ TICKS 0 ALLOT 1 TIME 9 (of 10) ]
[ time 1 ] Run JOB 0 at PRIORITY 1 [ TICKS 0 ALLOT 1 TIME 8 (of 10) ]
[ time 2 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 7 (of 10) ]
[ time 3 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 6 (of 10) ]
[ time 4 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 5 (of 10) ]
[ time 5 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 4 (of 10) ]
[ time 6 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 3 (of 10) ]
[ time 7 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 2 (of 10) ]
[ time 8 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 1 (of 10) ]
[ time 9 ] Run JOB 0 at PRIORITY 0 [ TICKS 0 ALLOT 1 TIME 0 (of 10) ]
[ time 10 ] FINISHED JOB 0

Final statistics:
  Job  0: startTime   0