maemo.org - Talk - BFS for the power kernel

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- - BFS for the power kernel (https://talk.maemo.org/showthread.php?t=58780)

BFS for the power kernel

Hi all!
I have completed a first attempt at applying the BFS scheduler patch to both the power and the stock 2.6.28-omap1 kernel.

The debian files here:
http://coreyoconnor.com/downloads/
Will install the equivalent of the latest kernel-power + BFS patches. This can be installed over kernel-power just fine; The package manager will consider it an update.

The patch for the stock kernel is located at:
http://coreyoconnor.com/downloads/ke...6.28-bfs.patch

I will be packaging up the patch for kernel-power shortly.

For me kernel-power + BFS works great. Still, since I just got this working only apply if you are OK reflashing your device if something goes wrong. This will uninstall in the same way as kernel-power.

The basic procedure for patching the stock kernel is similar to what is listed here:
http://natisbad.org/N900/n900-custom-kernel.html

suppose your stock kernel source is in the directory kernel-2.6.28-stock and the patch file is copied to the same directory then the procedure is

Code:

host# cd kernel-2.6.28-stock

host# patch -p1 < kernel-2.6.28-bfs.patch

At this point all patches should be applied OK. If not, well, something went wrong and you should let me know.

Now switch to the kernel-2.6.28-stock within the scratchbox environment

Code:

[sbox-FREMANTLE_ARMEL: ~/kernel-2.6.28-stock] > make rx51_defconfig

[sbox-FREMANTLE_ARMEL: ~/kernel-2.6.28-stock] > make oldconfig

[sbox-FREMANTLE_ARMEL: ~/kernel-2.6.28-stock] > make

This should build the kernel and all required modules just fine.

I'm going to leave the instructions incomplete. If you've flashed a kernel and updated the kernel modules on your device you should be fine. Otherwise.. try it with the stock kernel first!

How to package this up into a deb? Any pointers?

UPDATE
I have uploaded deb packages that are equivalent to the latest kernel-power packages plus the bfs patches.

Re: BFS scheduler for N900

Where are your benchmarks? Unless this patch makes things perceptibly faster, (and subjective is not a good enough metric) then what is the point?

Re: BFS scheduler for N900

Ask the Android kids what the point is.

Plus, if you had read up on BFS you'd know it's goal is to reduce latency and benchmarking latency is much harder than the typical benchmarking of a single process performance. Which is what most benchmarks tests. Good for testing overclocking, doesn't tell you much of anything in this case. I can think of a few good latency tests but the error bounds may be quite high. Unless somebody has a robot to push buttons for me....

Single process benchmarks, like a web browser javascript benchmark, are easy to schedule. So the difference between CFS and BFS should be negligable. Still, i might as well run a few. what benchmarks would you like to see?

One subjective difference that is significant enough to, IMO, be interesting is: the speed of my interactions with the phone are not diminished significantly when i am installing an application in the background. Not even the silly little graphical effects.

Re: BFS scheduler for N900

It would be really cool it this was incorporated into Power kernel. Is it possible to have more than one scheduler in one kernel and doing a switch (not necessarily in runtime but after a reboot maybe).

When n900 is on high load its responsiveness leaves a great deal to be desired. Its even worse when it is overclocked. It sometimes (ie after installing an app in HAM) stalls for 30 or more seconds not responding to any user activity. I would like to test if and how BFS affects that but I really don't want to loose Power kernel features.

Re: BFS scheduler for N900

Agreed. Integrating this patch into the power kernel would be great. I haven't checked out the power kernel patches yet, but I suspect they are largely orthogonal to this patch and should integrate easily.