-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

This is an update of the scheduler policy mechanism rewrite using the 
infrastructure of the current O(1) scheduler. Slight changes from the 
original design require a detailed description. The change to the original 
design has enabled all known corner cases to be abolished and cpu 
distribution to be much better maintained. It has proven to be stable in my 
testing and is ready for more widespread public testing now.


Aims:
 - Interactive by design rather than have interactivity bolted on.
 - Good scalability.
 - Simple predictable design.
 - Maintain appropriate cpu distribution and fairness.
 - Low scheduling latency for normal policy tasks.
 - Low overhead.
 - Making renicing processes actually matter for CPU distribution (nice 0 gets 
20 times what nice +20 gets)
 - Resistant to priority inversion
 - More forgiving of poor locking
 - Tunable for a server workload or computational tasks


Description:
 - All tasks start at a dynamic priority based on their nice value. They run 
for one RR_INTERVAL (nominally set to 10ms) and then drop one stair 
(priority). If they sleep before running again they get to run for 2 
intervals before being demoted a priority and so on until they get all their 
intervals at their best priority: 20 intervals for nice 0; 1 interval for 
nice +19.


- - The staircase elevation mechanism can be disabled and all tasks can simply 
descend stairs using the sysctl:

echo 0 > /proc/sys/kernel/interactive

this has the effect of maintaining cpu distribution much more strictly 
according to nice whereas the default mechanism allows bursts of cpu by 
interactive tasks before settling to appropriate cpu distribution.


- - The time tasks are cpu bound can be increased by using the sysctl:

echo 1 > /proc/sys/kernel/compute

which extends the RR_INTERVAL to 100ms and disables the staircase elevation 
improving conditions for pure computational tasks by optimising cache 
benefits and decreasing context switching (gains another 1.5% on kernbench).


Performance:
- - All cpu throughput benchmarks show equivalent or better performance than 
mainline. Note that disabling the interactive setting actually _worsens_ some 
benchmarks because of their dependence on yield() so I don't recommend 
disabling it unless you do a comparison first. 
- - Interactivity is approximately equivalent to mainline 2.6 but with faster 
application startup and no known behavioural quirks.


Comments and testing welcome.

 fs/proc/array.c        |    2
 include/linux/sched.h  |    8
 include/linux/sysctl.h |    2
 kernel/sched.c         |  676 
+++++++++++++------------------------------------
 kernel/sysctl.c        |   16 +
 5 files changed, 212 insertions(+), 492 deletions(-)

Can be downloaded here:
http://ck.kolivas.org/patches/2.6/2.6.7-rc2/patch-2.6.7-rc2-s6.3

and below
Con
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (GNU/Linux)

iD8DBQFAwzquZUg7+tp6mRURArBHAJ9SIBOKX6MYOdkJzdb+xRNnW82JQgCghLou
wXhrRsBsfY2BIqbLT1tUWcs=
=g1no
-----END PGP SIGNATURE-----