qmemman: use the fact that balloon driver retries

Apparently even if there is not enough xen memory to balloon up,
balloon driver will try to fulfill the request later, when
some memory is freed. Thus, in do_balloon, do not limit mem_set
to the available memory.

dom0/qmemman/qmemman.py

@@ -12,6 +12,7 @@ class DomainState:
         self.mem_used = None
         self.id = id
         self.meminfo_updated = False
+        self.last_target = 0
 
 class SystemState:
     def __init__(self):
@@ -64,6 +65,7 @@ class SystemState:
 #the below works (and is fast), but then 'xm list' shows unchanged memory value
     def mem_set(self, id, val):
         print 'mem-set domain', id, 'to', val
+        self.domdict[id].last_target = val
         self.xs.write('', '/local/domain/' + id + '/memory/target', str(val/1024))
 #can happen in the middle of domain shutdown
 #apparently xc.lowlevel throws exceptions too
@@ -118,24 +120,12 @@ class SystemState:
         self.domdict[domid].meminfo = self.parse_meminfo(val)
         self.domdict[domid].meminfo_updated = True
 
-    def adjust_inflates_to_xenfree(self, reqs, idx):
-        i = idx
-        memory_needed = 0
-        while i < len(reqs):
-            dom, mem = reqs[i]
-            memory_needed += mem - self.domdict[dom].memory_actual
-            i = i + 1
-        scale = 1.0*self.get_free_xen_memory()/memory_needed
-        dom, mem = reqs[idx]
-        scaled_req = self.domdict[dom].memory_actual + scale*(mem - self.domdict[dom].memory_actual)
-        return int(scaled_req)
-
     def is_balance_req_significant(self, memset_reqs):
         total_memory_transfer = 0
         MIN_TOTAL_MEMORY_TRANSFER = 150*1024*1024
         for rq in memset_reqs:
             dom, mem = rq
-            memory_change = mem - self.domdict[dom].memory_actual
+            memory_change = mem - self.domdict[dom].last_target
             total_memory_transfer += abs(memory_change)
         return total_memory_transfer > MIN_TOTAL_MEMORY_TRANSFER
 
@@ -155,22 +145,10 @@ class SystemState:
             return
             
         self.print_stats(xenfree, memset_reqs)
-        wait_before_first_inflate = False
-        i = 0
-        while i < len(memset_reqs):
-            dom, mem = memset_reqs[i]
-            memory_change = mem - self.domdict[dom].memory_actual
-            if memory_change < 0:
-                wait_before_first_inflate = True
-            else:
-                if wait_before_first_inflate:
-                    time.sleep(self.BALOON_DELAY)
-                    wait_before_first_inflate = False
-                #the following is called before _each_ inflate, to account for possibility that
-                #previously triggered memory release is in progress
-                mem = self.adjust_inflates_to_xenfree(memset_reqs, i)
+
+        for rq in memset_reqs:
+            dom, mem = rq
             self.mem_set(dom, mem)
-            i = i + 1
 
 #        for i in self.domdict.keys():
 #            print 'domain ', i, ' meminfo=', self.domdict[i].meminfo, 'actual mem', self.domdict[i].memory_actual