Re: [Xen-devel] atropos scheduler broken

[Diwaker Gupta <diwakergupta@xxxxxxxxx>]

Hi everyone,

Thats for the replies. Here's the update:

I used Ian's slurp program, with the params suggested by Steven.
Actually I had myself been thinking about the small values that I had
been using, but I was not sure what kind of impact they would have.

Here are the params I used (kind of an extreme case, but I just wanted
to be sure that if there was *some* change, I would be able to see
it):
xm atropos 1 10000    200000 50000 0
xm atropos 2 150000 200000 50000 0

So with these changes, here's a snippet of slurp's output from both
the VMs (VM2 is started a few seconds after VM1)

VM1:
CPU speed = 498 MHz
Slurped 90.72% CPU, TSC 6f70c573
Slurped 97.76% CPU, TSC 8d20a825
Slurped 98.77% CPU, TSC aacff8d9
Slurped 99.14% CPU, TSC c87f42c0
Slurped 99.36% CPU, TSC e62ef069
Slurped 98.22% CPU, TSC 03ded2ca
Slurped 98.71% CPU, TSC 218de63c
Slurped 76.88% CPU, TSC 3f40d8a3
Slurped 46.75% CPU, TSC 5cf03633
Slurped 39.86% CPU, TSC 7ab377bc
Slurped 47.18% CPU, TSC 986e75c5
Slurped 59.25% CPU, TSC b61ddba2
Slurped 51.54% CPU, TSC d3ccf714

VM2:
Slurped 53.26% CPU, TSC 52e34564
Slurped 55.14% CPU, TSC 70ae5af6
Slurped 57.19% CPU, TSC 8e5d809e
Slurped 42.62% CPU, TSC ac0cbb65
Slurped 42.80% CPU, TSC c9bc96d9
Slurped 56.01% CPU, TSC e7766b1c
Slurped 54.60% CPU, TSC 0530e391
Slurped 57.15% CPU, TSC 22e0003b
Slurped 56.18% CPU, TSC 40a1e234
Slurped 57.09% CPU, TSC 5e50c733
Slurped 56.75% CPU, TSC 7c125064
Slurped 55.62% CPU, TSC 99c1f384
Slurped 59.20% CPU, TSC b77143db
Slurped 47.35% CPU, TSC d5365862
Slurped 37.21% CPU, TSC f2e61a4e
Slurped 54.03% CPU, TSC 1095a58f
Slurped 59.79% CPU, TSC 2e675a34

Observations:
o When VM2 is not running, VM1 effectively gets *all* the CPU, even if
the xtratime bit is set to 0.
o When VM2 starts running, it looks like they get roughly equal CPU.
There doesn't seem to be any 'atropos' scheduling happening.

So how should one go about debugging Xen?
-- 
Diwaker Gupta
http://resolute.ucsd.edu/diwaker