By Grant Nelson Goals Virtual Ubuntu Compiling a New Kernel - PowerPoint PPT Presentation

A Kernel Compiling Adventure By Grant Nelson

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 2

 Read entire document before performing the steps laid out in this document.  Note that the methods in this document worked on my person computers but are not guaranteed to work on your own. 3

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 4

 Install Ubuntu  Compile a new kernel  Change the scheduler 5

 Since the scheduling algorithm is O(n), a large number of processes (~400) will cause each process duration (quantum) to be less than the schedule time. (May 2008)  One option is to lengthen the quantum value, but that can cause I/O processes to be slow.  Another is overhaul the scheduling algorithm, but that would take more work and knowledge of the system than I have. (Scheduler was overhauled around Sept 2008) 6

 Block scheduling uses the current scheduling method but increases the speed by a magnitude, therefore it is still O(n), but it allows around 4000 processes instead of 400.  More on that later… 7

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 8

 Don’t have a computer which you can install Ubuntu onto? Or don’t want to risk messing up your current system?  Use a virtual machine.  I was going to install Ubuntu in a VM (Virtual Machine) on my Dell laptop with Vista. 9

 Visit www.ubuntu.com  Download the latest version of Ubuntu Desktop Disk Image and save it. (I used 8.04)  This will take a while. (1-2 hours)  Continue while download is completing. 10

 Go to FileHippo.com and click on the Development Tools group.  Locate VirtualBox (typically x86) and download newest version.  Install VirtualBox just like any other Window application. 11

 Startup the VirtualBox  Click on New 12

 Click Next  Enter a Name for the new VM  I used Ubuntu, why not?  And select Ubuntu as the OS Type 13

 Select RAM for the new VM (~1GB) 14

 Click New  Create a Dynamically Expanding VHD (~10G) 15

 Once done setting up a new Virtual Machine the Guest OS needs to be installed. 16

 Click on Settings  Select CD/DVD-Rom  Set the recently downloaded Ubuntu Image 17

 Click Start  Click on Start or install Ubuntu 18

 Once Ubuntu starts click on the Install icon to begin install. 19

 Go through install options.  Most are straight forward.  Use default if answer is unknown. 20

 The install will take about an hour.  When complete don’t restart. Select to continue working with the LiveCD, then shut down completely. 21

 Go into Settings and remove Ubuntu CD Image.  Click start to boot up the newly installed Virtual Ubuntu. 22

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 23

 Log in as root for session su  Avoid a possible problem ▪ Some versions have a problem with the symbolic link /bin/sh pointing to /bin/dash rm – f /bin/sh ln – s /bin/bash /bin/sh  Update package database apt-get update 24

 Install needed packages apt-get install kernel-package libncurses5-dev fakeroot wget bzip2   Go shopping for your kernel source  www.kernel.org/pub/linux/kernel/v2.6/  I went with 2.6.24.1, because I could.  Download it using the release number. cd /usr/src wget http://www.kernel.org/pub/linux/kernel/ v2.6/linux-2.6.24.1.tar.bz2  25

 Unpack kernel sources tar xjf linux-2.6.24.1.tar.bz2  Create symbolic link ln – s linux-2.6.24.1 linux  Then go to sources cd /usr/src/linux  Copy the existing configuration cp /boot/config- ’uname –r’ ./. config 26

 To configure make menuconfig  First load an Alternate Configuration File: “. config ”.  I found it is best not to make changed from the current configuration.  On Exit, Save. 27

 To make a clean start  This will remove object files and cause a compile to take longer. make-kpkg clean  To compile the kernel  The first compile might take around 5 hours  On a virtual machine it can take up to twice as long. fakeroot make-kpkg --initrd --append-to-version=  -custom kernel_image kernel_headers  You may replace “custom” with any ID for the new kernel as long as it doesn’t contain whitespace. 28

 Discover the newly built packages cd /usr/src ; ls -l  Install new kernel packages dpkg – i linux-image-2.6.24.1-custom_2.6.24.1- custom-10.00.Custom_i386.deb  dpkg – i linux-headers-2.6.24.1-custom_2.6.24.1- custom-10.00.Custom_i386.deb   Check grub, the boot menu Vi /boot/grub/menu.lst 29

 Reboot Ubuntu shutdown – r now  While restarting, select the new kernel.  If installed correctly it should load properly.  Check that the new kernel is running. uname -r 30

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 31

 The after one successful compile, I added printk that would show up while booting.  The kernel compiled correctly but wouldn’t boot. I removed the printk recompiled but it still wouldn’t boot. Something was wrong with the configuration.  That is when I noticed another problem… 32

 While compiling Ubuntu in a VM, on my Dell laptop, the compiler used 100% CPU and the Disk I/O became very high.  The compile lasted for 5 hours the first time. After that it took 4 hours. Making it hard to test changes.  This also caused my computer to become incredibly hot … way too hot. 33

 I got an over-temp shutdown.  I didn’t want to damage my laptop, so I decided to install Ubuntu onto my older desktop with XP. 34

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 35

 Burn the previously downloaded Ubuntu CD Image to a CD. (I used Alcohol 120)  Backup your XP data, just incase.  Reboot computer  Startup into Ubuntu LiveCD 36

 Click Start or install Ubuntu  Select Language, Location, and Keyboard 37

 Give about 10.0GB for Linux  It might take a while to move Windows. 38

 Finish setting up personal options.  Once install is done, the CD will eject, remove it then restart.  Log into Ubuntu 39

 If all when well during boot Grub will show up given the option to boot into either Windows XP or Ubuntu.  I repeated “Compiling a New Kernel”  This time it worked instantly, even after I added the printk.  The first compile took 3 hours, all subsequent compiles took about 30 minutes to an hour.  And with better cooling the computer didn’t get as hot. 40

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 41

 The scheduler contains a linked list of scheduling groups: real-time, fair, and idle. sched_rt.c, sched_fair.c, sched_idletask.c   When one group returns a non-null process that process it placed into the ready to run queue.  Idle is always last, since it will always return a non-null: the idle process.  The real-time and fair groups have a linked list of processes. (pseudo-code similar to line 3631 sched.c) *group = static &sched_rt; while(1) { pid = group->pick_next_task(); if(pid!=null) schedule(pid); group = group->next; } 42

 The left shows the current real-time real-time scheduler with all static groups. fair static fair  The right shows a block fair idle scheduler which just brakes the fair group into several fair groups. These groups are sorted by their max and min idle processes. 43

 Make the fair scheduler no longer static and allocate memory for it when the fair scheduler is added to real-time scheduler.  At this point the scheduler should still work the exact same way.  Next add a max-nice and min-nice level which contains the current max and min “nice” (priority) levels. 44

 I would like to say everything continued working perfectly…  However, everything got fubar. 45

 Three weeks ago (around Nov 23 rd ) my desktop stopped functioning. While the Bios is starting up it fails to detect a keyboard.  This has no relation to the changes to the Linux scheduler.  I have tried all I could to recover my code and get my computer to startup, but I ran out of time.  If only I hadn’t started on a VM, if only my desktop hadn’t failed, or if only I had a whole year. 46

 Goals  Virtual Ubuntu  Compiling a New Kernel  Complications  Installing Ubuntu on WinXP  Building a Block Scheduler  Conclusion 47

D ON ’ T C OMPILE L INUX …unless you have way too much free time. 48