Re: [Xen-devel] Scheduler problem in XEN 3.4.0

[Pankaj Parakh <me.pankajparakh@xxxxxxxxx>]

Hi George,

Thanks for showing interest, First of all I'll try to setup debugging
environment for Xen, I also checked the mailing list of Ananth also I
know him personally, he has left it some where in middle.

I tried printk's and locking method to find out which function is
being called in schedule.c, I found the following sequence:-

schedule_init()
schedule_domain_init()
schedule_vcpu_init()
schedule_domain_init()
schedule_vcpu_init()
(from here no function is called from schedule.c, but system hangs)

I cant say what the problem is, I am only changing the sched_priv data
of vcpu struct, also my rr sched has only three functions viz
init_vcpu, destroy_vcpu, do_schedule.

I have attached the code as well.

Following are my doubts:

1. Is the above function sequence is right ? Why two times init_domain
is called during the boot.

2. Do a scheduler policy need to manipulate other part of vcpu struct
(other than sched_priv)

3. Is it necessary to maintain domain information inside scheduler policy

On Tue, Oct 13, 2009 at 5:17 PM, George Dunlap
<George.Dunlap@xxxxxxxxxxxxx> wrote:
>
> Pankaj,
>
> I haven't used the round-robin scheduler code in that book, but
> another guy named Ananth tried to use it unsuccessfully as well.  You
> can see some of that thread here (not sure why I can't find the
> original post):
>  http://lists.xensource.com/archives/html/xen-devel/2009-05/msg00004.html
>
> Most of us are not so interested in finding the bug in the books'
> code, but we are interested in helping *you* find it.  If you continue
> to do hypervisor work (and especially if you do anything with the
> scheduler), you're going to have to learn how to debug a hypervisor,
> which is often rather a pain in the neck.
>
> There is some advice in the thread linked to above about setting up a
> serial console.  You can add printk()'s around to find out what the
> sched_rr code is doing and where it's going wrong, and ask more
> questions on the list if you get stuck.  (Feel free to cc me to bring
> it to my attention, but always send it to the whole list.)
>
> Good luck,
>  -George
>
>
> On Mon, Oct 12, 2009 at 6:15 PM, Pankaj Parakh
> <me.pankajparakh@xxxxxxxxx> wrote:
> > Hi All,
> >
> > I am trying to learn about schedulers of XEN, so for a start I am
> > using XEN 3.4.0 and using book - The Definitive Guide to the Xen
> > Hypervisor - by David Chisnall, I have followed its steps to add
> > scheduler which is there in Chap. 12
> > But I dont know what is the problem, I am unable to boot with that
> > scheduler selected, I have been trying to debug this problem, but
> > kinda stuck in it.
> > The scheduler given in that book is a trivial round robin scheduler.
> >
> > Is the problem is with the code or with the procedure, I dont know that 
> > also.
> >
> > Plzz help me out of this.
> >
> > Thanks
> > Pankaj Parakh
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> >



--
Pankaj Parakh

Attachment: sched_trivial.c
Description: Text Data

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