[LITMUS^RT] Hash-Based Tie-Breaking for EDF

[Björn Brandenburg]

On Aug 27, 2012, at 9:58 PM, Glenn Elliott wrote:
> I've created a more robust patch for EDF tie-breaking.  You may view the patch on github (wip-robust-tie-break): 
> https://github.com/LITMUS-RT/litmus-rt/compare/wip-robust-tie-break

Looks very nice, thanks for the patch. I've just added a couple of minor comments using Github's comment feature; I hope you can see them.

	https://github.com/LITMUS-RT/litmus-rt/commit/077aaecac31331b65442275843932314049a2ceb

> fpmath.h is originally from an earlier version of Litmus (pre-Björn re-arch, I think).  I am not sure if it was ever mainlined into Litmus, or if it was only in a side-branch of Aaron Block's.

Not that it matters, but that's actually originally my code, from the original adaptive G-EDF implementation (I was the kernel monkey for that paper), which was done based on an early LITMUS^RT 2007.x in the spring and fall of 2007, I believe.

>  I have been maintaining my own fpmath.h for the last two years.  I have found it to be useful for implementing feedback control mechanisms for adaptive algorithms (Aaron used it for the same purposes).  My version of fpmath.h is pretty much like Aaron's, except I add support for 64-bit systems.  I think I also tweaked some #defines to allow use in liblitmus. 

Is it pulled in by the liblitmus build system? If not, I don't think we need the kernel ifdefs.

> 
> I'm afraid that I need to start working on more core activities, so I would like to wrap up this tie-break patch soon.  I would like us to decide exactly on what should go in staging (if anything).  If there isn't any interest, I'll just maintain this on my own on the side.  Please note that implementing different tie-breaking methods is pretty easy on top of the code I provide.  It just takes a few lines of code in edf_common.c and an update to Kconfig to add the new method.

I like the patch a lot and would like to merge it soon (preferably after the minor comments have been addressed). 

Thanks,
Björn