[libvirt] [PATCH 09/13] conf: Pre-calculate initial memory size instead of always calculating it

[Peter Krempa]

Add 'initial_memory' member to struct virDomainMemtune so that the
memory size can be pre-calculated once instead of inferring it always
again and again.

Separating of the fields will also allow finer granularity of decisions
in later patches where it will allow to keep the old initial memory
value in cases where we are handling incomming migration from older
versions that did not always update the size from NUMA as the code did
previously.

The change also requires modification of the qemu memory alignment
function since at the point where we are modifying the size of NUMA
nodes the total size needs to be recalculated too.

The refactoring done in this patch also fixes a crash in the hyperv
driver that did not properly initialize def->numa and thus
virDomainNumaGetMemorySize(def->numa) crashed.

In summary this patch should have no functional impact at this point.
---
 src/conf/domain_conf.c   | 52 +++++++++++++++++++++++++++++-------------------
 src/conf/domain_conf.h   |  3 +++
 src/libvirt_private.syms |  1 +
 src/qemu/qemu_domain.c   | 15 +++++++++-----
 4 files changed, 46 insertions(+), 25 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index a20ff2c..d2a13ca 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -3728,6 +3728,15 @@ virDomainDefRemoveDuplicateMetadata(virDomainDefPtr def)
 static int
 virDomainDefPostParseMemory(virDomainDefPtr def)
 {
+    size_t i;
+
+    if ((def->mem.initial_memory = virDomainNumaGetMemorySize(def->numa)) == 0) {
+        def->mem.initial_memory = def->mem.total_memory;
+
+        for (i = 0; i < def->nmems; i++)
+            def->mem.initial_memory -= def->mems[i]->size;
+    }
+
     if (virDomainDefGetMemoryInitial(def) == 0) {
         virReportError(VIR_ERR_XML_ERROR, "%s",
                        _("Memory size must be specified via <memory> or in the "
@@ -7699,19 +7708,7 @@ virDomainDefHasMemoryHotplug(const virDomainDef *def)
 unsigned long long
 virDomainDefGetMemoryInitial(virDomainDefPtr def)
 {
-    unsigned long long ret;
-    size_t i;
-
-    /* return NUMA memory size total in case numa is enabled */
-    if ((ret = virDomainNumaGetMemorySize(def->numa)) > 0) {
-        return ret;
-    } else {
-        ret = def->mem.total_memory;
-        for (i = 0; i < def->nmems; i++)
-            ret -= def->mems[i]->size;
-    }
-
-    return def->mem.total_memory;
+    return def->mem.initial_memory;
 }


@@ -7720,13 +7717,30 @@ virDomainDefGetMemoryInitial(virDomainDefPtr def)
  * @def: domain definition
  * @size: size to set
  *
- * Sets the total memory size in @def.
+ * Sets the total memory size in @def. This function should be used only by
+ * hypervisors that don't support memory hotplug.
  */
 void
 virDomainDefSetMemoryTotal(virDomainDefPtr def,
                            unsigned long long size)
 {
     def->mem.total_memory = size;
+    def->mem.initial_memory = size;
+}
+
+
+/**
+ * virDomainDefSetMemoryInitial:
+ * @def: domain definition
+ * @size: size to set
+ *
+ * Sets the initial memory size (without memory modules) in @def.
+ */
+void
+virDomainDefSetMemoryInitial(virDomainDefPtr def,
+                             unsigned long long size)
+{
+    def->mem.initial_memory = size;
 }


@@ -7744,12 +7758,10 @@ virDomainDefGetMemoryActual(virDomainDefPtr def)
     unsigned long long ret;
     size_t i;

-    if ((ret = virDomainNumaGetMemorySize(def->numa)) > 0) {
-        for (i = 0; i < def->nmems; i++)
-            ret += def->mems[i]->size;
-    } else {
-        ret = def->mem.total_memory;
-    }
+    ret = def->mem.initial_memory;
+
+    for (i = 0; i < def->nmems; i++)
+        ret += def->mems[i]->size;

     return ret;
 }
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 74c29bd..ab250bd 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -2145,6 +2145,8 @@ struct _virDomainMemtune {
     /* total memory size including memory modules in kibibytes, this field
      * should be accessed only via accessors */
     unsigned long long total_memory;
+    /* initial memory size in kibibytes = total_memory excluding memory modules*/
+    unsigned long long initial_memory;
     unsigned long long cur_balloon; /* in kibibytes, capped at ulong thanks
                                        to virDomainGetInfo */

@@ -2324,6 +2326,7 @@ struct _virDomainDef {

 unsigned long long virDomainDefGetMemoryInitial(virDomainDefPtr def);
 void virDomainDefSetMemoryTotal(virDomainDefPtr def, unsigned long long size);
+void virDomainDefSetMemoryInitial(virDomainDefPtr def, unsigned long long size);
 unsigned long long virDomainDefGetMemoryActual(virDomainDefPtr def);
 bool virDomainDefHasMemoryHotplug(const virDomainDef *def);

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index d31687d..c87efa1 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -227,6 +227,7 @@ virDomainDefParseFile;
 virDomainDefParseNode;
 virDomainDefParseString;
 virDomainDefPostParse;
+virDomainDefSetMemoryInitial;
 virDomainDefSetMemoryTotal;
 virDomainDeleteConfig;
 virDomainDeviceAddressIsValid;
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 8f9b40c..f92e1d3 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -3380,6 +3380,7 @@ qemuDomainGetMemorySizeAlignment(virDomainDefPtr def ATTRIBUTE_UNUSED)
 int
 qemuDomainAlignMemorySizes(virDomainDefPtr def)
 {
+    unsigned long long initialmem = 0;
     unsigned long long mem;
     unsigned long long align = qemuDomainGetMemorySizeAlignment(def);
     size_t ncells = virDomainNumaGetNodeCount(def->numa);
@@ -3387,13 +3388,17 @@ qemuDomainAlignMemorySizes(virDomainDefPtr def)

     /* align NUMA cell sizes if relevant */
     for (i = 0; i < ncells; i++) {
-        mem = virDomainNumaGetNodeMemorySize(def->numa, i);
-        virDomainNumaSetNodeMemorySize(def->numa, i, VIR_ROUND_UP(mem, align));
+        mem = VIR_ROUND_UP(virDomainNumaGetNodeMemorySize(def->numa, i), align);
+        initialmem += mem;
+        virDomainNumaSetNodeMemorySize(def->numa, i, mem);
     }

-    /* align initial memory size */
-    mem = virDomainDefGetMemoryInitial(def);
-    virDomainDefSetMemoryTotal(def, VIR_ROUND_UP(mem, align));
+    /* align initial memory size, if NUMA is present calculate it as total of
+     * individual aligned NUMA node sizes */
+    if (initialmem == 0)
+        initialmem = VIR_ROUND_UP(virDomainDefGetMemoryInitial(def), align);
+
+    virDomainDefSetMemoryInitial(def, initialmem);

     def->mem.max_memory = VIR_ROUND_UP(def->mem.max_memory, align);

-- 
2.4.5