[LITMUS^RT] 0 period, negative lateness for recorded tasks -- Sisu

[Sisu Xi]

Hi, all:

I was trying to run some experiments in Litmus in a VM. However, all the
number I got was negative for the task lateness.
And all jobs are showing 0 for the period, and shows CPU=-1.

here is my setup:
HostOS: Normal Linux 3.4.35
Xen: 4.1.4
GuestOS: root at litmus1:~# uname -a
Linux litmus1 3.0.0-litmus #3 SMP PREEMPT Wed Apr 17 11:02:36 CDT 2013
x86_64 x86_64 x86_64 GNU/Linux

Here is the scripts to run experiments:
root at litmus1:~# cat 200_1_MPR_Dom1.sh
rtspin -s 0.98 8 10 100 &
rtspin -s 0.98 8 10 100 &
rtspin -s 0.98 8 10 100 &
rtspin -s 0.98 8 10 100 &
rtspin -s 0.98 8 10 100 &
st_trace 200_1_MPR_Dom1
killall rtspin

I modified the st_trace so it stopped after 20 seconds. This is the only
modification I made.
Here is the script output:
root at litmus1:~# ./200_1_MPR_Dom1.sh
CPU 0: 1382 > st-200_1_MPR_Dom1-0.bin [0]
CPU 1: 1383 > st-200_1_MPR_Dom1-1.bin [0]
CPU 2: 1384 > st-200_1_MPR_Dom1-2.bin [0]
CPU 3: 1385 > st-200_1_MPR_Dom1-3.bin [0]
CPU 4: 1386 > st-200_1_MPR_Dom1-4.bin [0]
Press Enter to end tracing...
Ending Trace...
Disabling 10 events.
Disabling 10 events.
Disabling 10 events.
Disabling 10 events.
Disabling 10 events.
[10462.657790] Failed trace writes: 0
/dev/litmus/sched_trace3: 192096 bytes read.
[10462.658101] Failed trace writes: 0
/dev/litmus/sched_trace1: 192096 bytes read.
[10462.663359] Failed trace writes: 0
/dev/litmus/sched_trace0: 192120 bytes read.
[10462.663989] Failed trace writes: 0
/dev/litmus/sched_trace4: 192168 bytes read.
[10462.665088] Failed trace writes: 0
/dev/litmus/sched_trace2: 192168 bytes read.

However, here is the result using st_job_stats
root at litmus1:~# st_job_stats st-200_1_MPR_Dom1-0.bin | head
# Task,   Job,     Period,   Response, DL Miss?,   Lateness,  Tardiness
# task NAME=<unknown> PID=1369 COST=0 PERIOD=0 CPU=-1
  1369,   509,          0,    7900519,        0,   -2099481,          0
  1369,   510,          0,    7895709,        0,   -2104291,          0
  1369,   511,          0,    7893512,        0,   -2106488,          0
  1369,   512,          0,    7898799,        0,   -2101201,          0
  1369,   513,          0,    7902469,        0,   -2097531,          0
  1369,   514,          0,    7902914,        0,   -2097086,          0
  1369,   515,          0,    7894691,        0,   -2105309,          0
  1369,   516,          0,    7897107,        0,   -2102893,          0

And the data on other cpus shows the same negative value for lateness..


In Xen, I am using tsc_mode=1, which is:
- tsc_mode=1 (always emulate). All rdtsc instructions are emulated;
   this is the best choice when TSC-sensitive apps are running and
   it is necessary to understand worst-case performance degradation
   for a specific hardware environment.

this should be good for tsc-sensitive applications..

Any ideas?

Thanks very much!

Sisu






-- 
Sisu Xi, PhD Candidate

http://www.cse.wustl.edu/~xis/
Department of Computer Science and Engineering
Campus Box 1045
Washington University in St. Louis
One Brookings Drive
St. Louis, MO 63130
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