[Xen-devel] Problem passing arguments from main.py to a new scheduler

[Martin Dommermuth <mailmartin@xxxxxx>]

Hi there,

as part of my diploma thesis I am currently extending Xen with
a new scheduler with some real time features. 

As I didn't have any prior knowledge of Python I am having a hard
time understanding the path a call to xm takes through Xen.

It starts in my function in main.py where I check whether the
correct options are set.  

-----------------main.py
def xm_sched_rtbe(args):
    """Get/Set options for RTBE Scheduler."""
    print "called xm_sched_rtbe() argv:"
    print args
    correctSyntax = False

    try:
        (opts, params) = getopt.getopt(args, "o:m:d:t:e:p:s:q:i:b:")
        print opts
        print params
       
    except getopt.GetoptError, opterr:
        print opts
        print params
        err(opterr)
        usage('sched-rtbe')
    if serverType == SERVER_XEN_API:
            err("ServerType SERVER_XEN_API not supported by RTBE.")

    result   = 1
    op       = None
    mtf      = None
    domain   = None
    tp       = None
    event    = None
    prio     = None
    start    = None
    quantum  = None
    interval = None
    mtf_id   = None

    for o, a in opts:
        if o in ["-o"]:
            op       = a
        elif o in ["-m"]:
            mtf      = int(a)
        elif o in ["-d"]:
            domain   = int(a)
        elif o in ["-t"]:
            tp       = int(a)
        elif o in ["-e"]:
            event    = int(a)
        elif o in ["-p"]:
            prio     = int(a)
        elif o in ["-s"]:
            start    = int(a)
        elif o in ["-q"]:
            quantum   =  int(a)
        elif o in ["-i"]:
             interval = int(a)
        elif o in ["-b"]:
             mtf_id = int(a);

    if op == "mtf":
        op = RTBE_MTF
        if mtf is None:
            err("Operation 'mtf' needs -m set")
        else:
            correctSyntax = True    
    elif op == "bind":
        op = RTBE_BIND_TP
        if domain is None or tp is None or prio is None:
            err("Operation 'bind' needs -d, -t and -p set")
        else:
            correctSyntax = True
    elif op == "event":
        op = RTBE_BIND_EVENT
        if domain is None or event is None or quantum is None or interval is 
None:
            err("Operation 'event' needs -d, -q and -i set")
        else:
            correctSyntax = True
    elif op == "add":
        op = RTBE_ADD
        if tp is None or start is None or quantum is None:
            err("Operation 'add' needs -t, -q and -s set")
        else:
            correctSyntax = True        
    elif op == "del":
        op = RTBE_DEL
        if mtf_id is None:
            err("Operation 'del' needs -b set")
        else:
            domain = 0
            correctSyntax = True
    elif op == "print":
            op = RTBE_PRINT
            correctSyntax = True
    else:
        err("Operation must be set: -o {mtf|bind|event|add|del|print}")
        result = 0
    if correctSyntax == True:        
        result = 
server.xend.domain.sched_rtbe_set(op,domain,mtf,tp,event,prio,start,quantum,interval,mtf_id)
        print "called server.xend.domain.sched_rtbe_set. result: %s" % result   
                                      
    if result != 0:
                err(str(result))
-----------------end

My call to server.xend.domain.sched_rtbe_set() seems to never make
it into XendDomain.py, which looks like this:


-----------------XendDomain.py
def 
domain_sched_rtbe_set(self,op,domain,mtf,tp,event,prio,start,qantum,interval,mtf_id):
        """Set rtbe scheduler parameters for a domain."""
        print "called domain_sched_rtbe_set()"
        #assert type(op)       == int
    
        if op is None:
            return None    
        try:
            if op == RTBE_MTF:
                print "calling xc.sched_rtbe_mtf_set()"
                # we use Dom0 for commands which don't need a domain, because
                # of the signature of adjust from struct scheduler:
                # int (*adjust) (struct domain *, struct 
xen_domctl_scheduler_op *) 
                dominfo = self.domain_lookup_nr(0)
                rc = xc.sched_rtbe_mtf_set(op,dominfo.getDomid(), mtf)          
      
                return rc
            elif op == RTBE_BIND_TP:
                dominfo = self.domain_lookup_nr(domain)
                rc = xc.sched_rtbe_bind_tp(op, dominfo.getDomid(), tp, prio)
            elif op == RTBE_BIND_EVENT:
                dominfo = self.domain_lookup_nr(domain)
                rc = xc.sched_rtbe_bind_event(op, dominfo.getDomid(), event, 
quantum, interval)
            elif op == RTBE_ADD:
                dominfo = self.domain_lookup_nr(0)
                rc = xc.sched_rtbe_add(op, dominfo.getDomid(), tp,start,quantum)
            elif op == RTBE_DEL:
                dominfo = self.domain_lookup_nr(0)
                rc = xc.sched_rtbe_del(op, dominfo.getDomid(),mtf_id )
            elif op == RTBE_PRINT:
                dominfo = self.domain_lookup_nr(0)
                rc = xc.sched_rtbe_print(op, dominfo.getDomid())    
        except Exception, ex:
            log.exception(ex)
            raise XendError(str(ex))

-----------------------------------
The print statement is never executed. All I get is:
Error: (22, 'Invalid argument') and then usage() is called.

Now to the part I do not get: In SrvDomain.py I defined:

    def op_domain_sched_rtbe_set(self, _, req):
        fn = FormFn(self.xd.domain_sched_rtbe_set,
                    [['op', 'int'],
                     ['domain', 'int'],
                     ['mtf', 'int'],
                     ['tp', 'int'],
                     ['event', 'int'],
                     ['prio', 'int'],
                     ['start', 'int'],
                     ['quantum', 'int'],
                     ['interval', 'int'],
                     ['mtf_id', 'int']])
        val = fn(req.args)
        return val

Is this right? Are there any other places at which I have to define
the function? 

This stuff with FormFn is a bit too Python-Voodoo for me :)

Thanks!
MartinD:

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