OPERATING SYSTEM: DESIGN AND IMPLEMENT FINAL PROPOSAL SCHEDULER 周長毅, 周榆豐

Outline  Motivation  Purpose  Theory  O(1) Scheduler  CFS, Complete Fair Scheduler  BFS, Brain Fuck Scheduler  Testing - Linux  Result

Motivation  Wish to enhance smartphone’s performance by modifying operating system’s kernel.  But we encountered some problem when patching kernel.  So testing platform move to Linux on PC from Android on HTC Evo 3D.  Still use regular benchmark to test performance.

Purpose  More familiar with Operating System’s Scheduler we use in common.  Compare the special feature, pros and cons in actual use.

Theory  O(1) Scheduler  CFS, Complete Fair Scheduler  BFS, Brain Fuck Scheduler

O(1) Scheduler ActiveExpired Task1 Task2Task3 Task4Task5Task6 Go to Blank Page

CFS Go to Blank Page

BFS Key Point : jiffies + (prio_ratio * rr_interval) Go to Blank Page

Testing – Machine  Testing Machine ：  CPU = Intel Xeon E v2 (3.3GHz, 4C8T)  RAM = 8GB DDR x4  MB = Gigabyte GA-PH67-UD3-B3  HDD = Hitachi HDS723020BLA642 (2TB 7200rpm)  Virtual Machine software = Vmware Player  Testing Software = Phoronix Test Suite v5.2.0  8 threads and 12GB RAM are allocated for guest system

Testing – How to play with BFS?  You need to prepare  Kernel Source Code from kernel.org  BFS patch that support your kernel’s version from BFS’s author.  Other component you need to compile Linux kernel.  Time, of course.

Testing – How to play with BFS?  Use “Patch” command to patch BFS into kernel.  You will see option about BFS in “make menuconfig” if no error is encountered.

Testing – How to play with BFS?  If you encountered errors you may see like this.  That’s why we can’t test on HTC Evo 3D.  But some foreign programmer DID this on other Android devices.  And the most exaggerated is you can’t patch the kernel version on kernel.org.

Testing – Testing software  Becouse we are not familiar with Linux and don’t know how to benchmark in Linux, so we use “Phoronix Test Suite” to benchmark.  “Phoronix Test Suite” has tons of options we can choose, but we don’t know So we use ”Run Complex System Test” in main menu to benchmark

Testing – Testing option  In ”Run Complex System Test”, it will benchmark 4 item, they are:  PostMark: Simulate a small server and test about it.  RAMspeed SMP: Benchmark the memory bandwidch.  C-Ray: Bench the performance of CPU’s flouting point calculation.  Apache Benchmark: Simulate some environments and test the response performance about Apache.

Result Completely Fair SchedulerBrain Fuck Scheduler

Result  But CFS’s performance is 32% highter than BFS in “Apache Benchmark”  BFS’s performance is 11% highter than CFS in “PostMark”.

END That’s all.

O(1)O(1) CFS BFSCFSBFS