Re: [PATCH] Fix xm commands for inactive domains

["Daniel P. Berrange" <berrange@redhat.com>]

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On Wed, Dec 13, 2006 at 03:38:09PM +0000, Daniel P. Berrange wrote:
> 
> The commands 'mem-set' 'mem-max' and 'vcpu-set' are all broken when used 
> against an inactive domain. The backend implementation of these commands
> typically updates the in-memory config held by XenD, and does a hypercall
> or xenstore write to update the live guest. Obviously the latter part fails
> with inactive guests. The changes are also not persisted to disk.
> 
> The attached patch ensures that the hypercalls/xenstore writes are not
> tried for inactive guests. It will also write out the changes to disk
> so config changes to inactive guests are preserved across XenD restarts.
> 
> Normally memory_dynamic_min/max  and online_vcpus are picked up from the
> running domain state. This doesn't apply for inactive guests, so when 
> changing config for inactive guests, we also update those 3 parameters to
> match the new settings. 
> 
> So, at the end of all this, I can do:
> 
> 1. Define an inactive domain...
> 
>   # xm new demo
>   # xm list demo
>   Name                                      ID   Mem VCPUs      State   Time(s)
>   demo                                           410     1                 0.0
>   # xm list --long demo | grep mem
>       (memory 410)
>       (maxmem 800)
>       (shadow_memory 0)
>       (memory_dynamic_min 410)
>       (memory_dynamic_max 800)
> 
> 2. Change its memory config...
> 
>   # xm mem-set demo 500
>   # xm mem-max demo 1000
>   # xm list --long demo | grep mem
>       (memory 500)
>       (maxmem 1000)
>       (shadow_memory 0)
>       (memory_dynamic_min 500)
>       (memory_dynamic_max 1000)
>   # xm list demo
>   Name                                      ID   Mem VCPUs      State   Time(s)
>   demo                                           500     1                 0.0
> 
> 3. Change its cpu config...
> 
>   # xm vcpu-set demo 8
>   # xm list --long demo | grep vcpu
>       (vcpus 8)
>       (online_vcpus 8)
>   # xm list demo
>   Name                                      ID   Mem VCPUs      State   Time(s)
>   demo                                           500     8                 0.0
> 
> 4. Start it with new settings...
> 
>   # xm start demo
>   # xm list demo
>   Name                                      ID   Mem VCPUs      State   Time(s)
>   demo                                      22   500     8     -b----      0.7
> 
> NB, the patch is structured so there is no functional change for active
> guests, to minimise risk of regression in this 3.0.4 freeze. I think this
> is really important to get working in 3.0.4 since inactive domain support
> is of pretty limited usefullness as it currently stands.  Hopefully in 3.0.5
> the XenAPI will make it possible to change all aspects of an inactive guest
> config.
> 
>   Signed-off-by: Daniel P. Berrange  <berrange@redhat.com>

There was one final problem I've just also fixed - for some reason the
SEXPR api to change max memory was calling into XenDomain instead of
XenDomainInfo directly. This meant it needed a domid - which doesn't
exist in inactive domain case. So this updated version of the patch also
fixed SrvDomain.py  to call the XenDomainInfo object it already has 
directly - this matches the style of the rest of the method in SrvDomain.py

The attached patch contains my original patch + this SrvDomain.py fix.
Now, not only does 'xm' work correctly, but libvirt can manage inactive
domains & their config settings too.

 Signed-off-by: Daniel P. Berrange  <berrange@redhat.com>

Regards,
Dan.
-- 
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diff -ruNp xen-unstable.hg-12895/tools/python/xen/xend/server/SrvDomain.py xen-unstable.hg-12895.new/tools/python/xen/xend/server/SrvDomain.py
--- xen-unstable.hg-12895/tools/python/xen/xend/server/SrvDomain.py	2006-12-11 17:30:50.000000000 -0500
+++ xen-unstable.hg-12895.new/tools/python/xen/xend/server/SrvDomain.py	2006-12-13 12:17:05.000000000 -0500
@@ -160,12 +160,9 @@ class SrvDomain(SrvDir):
         return val
 
     def op_maxmem_set(self, _, req):
-        fn = FormFn(self.xd.domain_maxmem_set,
-                    [['dom',    'int'],
-                     ['memory', 'int']])
-        val = fn(req.args, {'dom': self.dom.domid})
-        return val
-
+        return self.call(self.dom.setMemoryMaximum,
+                         [['memory', 'int']],
+                         req)
     
     def call(self, fn, args, req):
         return FormFn(fn, args)(req.args)
diff -ruNp xen-unstable.hg-12895/tools/python/xen/xend/XendDomainInfo.py xen-unstable.hg-12895.new/tools/python/xen/xend/XendDomainInfo.py
--- xen-unstable.hg-12895/tools/python/xen/xend/XendDomainInfo.py	2006-12-11 17:31:28.000000000 -0500
+++ xen-unstable.hg-12895.new/tools/python/xen/xend/XendDomainInfo.py	2006-12-13 10:32:16.000000000 -0500
@@ -606,8 +606,34 @@ class XendDomainInfo:
             raise XendError('Invalid memory size')
         
         self.info['memory_static_min'] = target
-        self.storeVm("memory", target)
-        self.storeDom("memory/target", target << 10)
+        if self.domid >= 0:
+            self.storeVm("memory", target)
+            self.storeDom("memory/target", target << 10)
+        else:
+            self.info['memory_dynamic_min'] = target
+            xen.xend.XendDomain.instance().managed_config_save(self)
+
+    def setMemoryMaximum(self, limit):
+        """Set the maximum memory limit of this domain
+        @param limit: In MiB.
+        """
+        log.debug("Setting memory maximum of domain %s (%d) to %d MiB.",
+                  self.info['name_label'], self.domid, limit)
+
+        if limit <= 0:
+            raise XendError('Invalid memory size')
+
+        self.info['memory_static_max'] = limit
+        if self.domid >= 0:
+            maxmem = int(limit) * 1024
+            try:
+                return xc.domain_setmaxmem(self.domid, maxmem)
+            except Exception, ex:
+                raise XendError(str(ex))
+        else:
+            self.info['memory_dynamic_max'] = limit
+            xen.xend.XendDomain.instance().managed_config_save(self)
+
 
     def getVCPUInfo(self):
         try:
@@ -876,18 +902,23 @@ class XendDomainInfo:
 
     def setVCpuCount(self, vcpus):
         self.info['vcpu_avail'] = (1 << vcpus) - 1
-        self.storeVm('vcpu_avail', self.info['vcpu_avail'])
-        # update dom differently depending on whether we are adjusting
-        # vcpu number up or down, otherwise _vcpuDomDetails does not
-        # disable the vcpus
-        if self.info['vcpus_number'] > vcpus:
-            # decreasing
-            self._writeDom(self._vcpuDomDetails())
-            self.info['vcpus_number'] = vcpus
+        if self.domid >= 0:
+            self.storeVm('vcpu_avail', self.info['vcpu_avail'])
+            # update dom differently depending on whether we are adjusting
+            # vcpu number up or down, otherwise _vcpuDomDetails does not
+            # disable the vcpus
+            if self.info['vcpus_number'] > vcpus:
+                # decreasing
+                self._writeDom(self._vcpuDomDetails())
+                self.info['vcpus_number'] = vcpus
+            else:
+                # same or increasing
+                self.info['vcpus_number'] = vcpus
+                self._writeDom(self._vcpuDomDetails())
         else:
-            # same or increasing
             self.info['vcpus_number'] = vcpus
-            self._writeDom(self._vcpuDomDetails())
+            self.info['online_vcpus'] = vcpus
+            xen.xend.XendDomain.instance().managed_config_save(self)
 
     def getLabel(self):
         return security.get_security_info(self.info, 'label')
diff -ruNp xen-unstable.hg-12895/tools/python/xen/xend/XendDomain.py xen-unstable.hg-12895.new/tools/python/xen/xend/XendDomain.py
--- xen-unstable.hg-12895/tools/python/xen/xend/XendDomain.py	2006-12-11 17:30:50.000000000 -0500
+++ xen-unstable.hg-12895.new/tools/python/xen/xend/XendDomain.py	2006-12-13 10:32:10.000000000 -0500
@@ -1337,11 +1337,7 @@ class XendDomain:
         dominfo = self.domain_lookup_nr(domid)
         if not dominfo:
             raise XendInvalidDomain(str(domid))
-        maxmem = int(mem) * 1024
-        try:
-            return xc.domain_setmaxmem(dominfo.getDomid(), maxmem)
-        except Exception, ex:
-            raise XendError(str(ex))
+        dominfo.setMemoryMaximum(mem)
 
     def domain_ioport_range_enable(self, domid, first, last):
         """Enable access to a range of IO ports for a domain

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