Fairness-oriented Scheduler for Asymmetric Multicores

by Changdae Kim (cdkim@calab.kaist.ac.kr)

Overview

Schedule cores in a multicore environment.

How to install

Download Linux kernel 3.7.3 and patch linux-3.7.3-fairamp.patch.
Compile and install the patched kernel on the system. Note that the following options must be enabled to use fairness-oriented scheduler.
- General setup -> Fairness-oriented scheduling for asymmetric multi-cores (FAIRAMP)
- General setup -> FAIRAMP really DO the scheduling
- General setup -> FAIRAMP use fast-core-first policy
- General setup -> FAIRAMP measures instruction per seconds
Go to tools/fairamp in the patched kernel source tree.
Install the tool to using fairness-oriented scheduler.
```
$ make
$ sudo make install
```

How to run

Run the following command and refer to the usage
```
$ fairamp -h
```
Sample run command is here.
```
$ fairamp -c test.comm
```
(test.comm is included in tools/fairamp/)
If you want to see less messages, use the follow command. The other options are same with fairamp.
```
$ fairamp.quiet -c test.comm
```

NOTE

This software works on x86_64 architecture, that is, 64-bit processors from Intel or AMD.
This version is tested and validated using Ubuntu 12.04.5 and gcc 4.6.3. Some problem may occurs on other environments.
DVFS should be available for the system.
CPU hotplug is enabled OR all cores should be turned on.
Detecting hard lockups must be disabled due to confliction on using performance counters. You should clear the following kernel option: Kernel hacking -> Kernel debugging -> Detect Hard and Soft Lockups

Trouble Shooting

Debug the Kernel

Make sure to configure following options when compile the target kernel.

CONFIG_RANDOMIZE_BASE=n
CONFIG_FRAME_POINTER=y
CONFIG_KGDB=y
CONFIG_KGDB_SERIAL_CONSOLE=y
CONFIG_KGDB_KDB=y
CONFIG_KDB_KEYBOARD=y

Enable the sys request.

echo 1 > /proc/sys/kernel/sysrq

To enable debug sys request,

echo ttyS0 > /sys/module/kgdboc/parameters/kgdboc

Send to be used by KGDB.

echo g > /proc/sysrq-trigger

For more information, please refer to our paper,

Changdae Kim and Jaehyuk Huh. Exploring the Design Space of Fair Scheduling Supports for Asymmetric Multicore Systems. IEEE Transactions on Computers, vol. 67, no. 8, pp. 1136-1152, August 2018.

https://ieeexplore.ieee.org/document/8265024

Future Works

Testing the test script to work on the original environment.
Merge and update the software to work on lastest versions. (Targeting Ubuntu 18.04 and Linux 5.4)

casys-kaist/fairamp