Re: [Xen-devel] ARINC653

["Simon Martin" <smartin@xxxxxxxxxxxx>]

Hi Nate,

 

I finally got round to pulling in the latest and greatest patches and after a few silly mistakes (RTFM) I now have a working system. As mentioned before I have 2 pools:

 

smartin@smartin-xen:~/projects/trio/xen/pv499$ sudo xl cpupool-list
Name               CPUs   Sched     Active   Domain count
Pool-0               3    credit       y          1
pv499                1  arinc653       y          1

 

After loading the domU into the pv499 and running the program that configures the arinc scheduler I get this:

 

smartin@smartin-xen:~/projects/trio/xen/pv499$ sudo xl list
Name                                        ID   Mem VCPUs      State   Time(s)
Domain-0                                     0  2967     4     r-----     117.2
pv499                                       24    32     1     r-----     373.0

 

So far so good. Now looking at the timings things are not too different from when I was using the credit scheduler. Running a single shot timer at a period of 250 Âs gives me a jitter in the timer handler latency in the range [3.5 Âs, 45 Âs]. This makes it look like the problem in the jitter is not the scheduling but the underlying hypervisor. It is going off to do things on this CPU which is causing the deadlines not to be met.

 

So unless I am doing something silly it looks like I will have to go to RT-Xen to get better timings. For the moment I'm going to leave this and go on to getting more of my operating system working.

 

Regards.

 

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