glitch1 results - 2.6.21.3-cfs-v15

glitch1 results - 2.6.21.3-cfs-v15

[Bill Davidsen]

I have added cfs15 to the chart at 
www.tmr.com/~davidsen/sched_smooth_05.html and updated the source of the 
test at www.tmr.com/~public/source if anyone wants to run test on their 
hardware.

I feel that on my hardware cfs-13 was the smoothest for this test and 
for watching videos. Even relatively light load:
   nice -10 make -j4 -s
of a kernel would cause jumps on the video, gears or youtube.

-- 
Bill Davidsen <davidsen@tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

Re: glitch1 results - 2.6.21.3-cfs-v15

[Ingo Molnar]

* Bill Davidsen <davidsen@tmr.com> wrote:

> I have added cfs15 to the chart at 
> www.tmr.com/~davidsen/sched_smooth_05.html and updated the source of 
> the test at www.tmr.com/~public/source if anyone wants to run test on 
> their hardware.

thanks!

> I feel that on my hardware cfs-13 was the smoothest for this test and 
> for watching videos. Even relatively light load:
>   nice -10 make -j4 -s
> of a kernel would cause jumps on the video, gears or youtube.

ah, found this bug i think! Does the patch below fix it for you and does 
it bring back v13's smoothness for the reniced kernel build?

	Ingo

Index: linux/kernel/sched_fair.c
===================================================================
--- linux.orig/kernel/sched_fair.c
+++ linux/kernel/sched_fair.c
@@ -385,6 +374,7 @@ static void enqueue_sleeper(struct rq *r
 	 * during the whole sleep period:
 	 */
 	delta_fair = div64_s(delta_fair * load, load + p->load_weight);
+	delta_fair = div64_s(delta_fair * p->load_weight, NICE_0_LOAD);
 
 	prev_runtime = p->wait_runtime;
 	__add_wait_runtime(rq, p, delta_fair);