[libvirt] [RFC/PATCH v1] Adding entry for cpu tunable shares in xml

[Nikunj A. Dadhania]

From: Nikunj A. Dadhania <nikunj at linux.vnet.ibm.com>

Make cpu share persistent and add support for parsing them.

docs/formatdomain.html.in: Document cputune element
src/conf/domain_conf.c,src/conf/domain_conf.h: Add cputune element parsing
src/lxc/lxc_controller.c: Use the parsed cputune shares value
src/qemu/qemu_cgroup.c: Use the parsed cputune shares value

Signed-off-by: Nikunj A. Dadhania <nikunj at linux.vnet.ibm.com>
---
 docs/formatdomain.html.in |   11 +++++++++++
 src/conf/domain_conf.c    |   14 ++++++++++++++
 src/conf/domain_conf.h    |    3 +++
 src/lxc/lxc_controller.c  |   10 ++++++++++
 src/qemu/qemu_cgroup.c    |   15 +++++++++++++++
 5 files changed, 53 insertions(+), 0 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 55e2cbd..522dc06 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -280,6 +280,9 @@
     <swap_hard_limit>2097152</swap_hard_limit>
     <min_guarantee>65536</min_guarantee>
   </memtune>
+  <cputune>
+    <shares>1024</shares>
+  </cputune>
   <vcpu cpuset="1-4,^3,6" current="1">2</vcpu>
   ...</pre>
 
@@ -317,6 +320,14 @@
       <dd> The optional <code>min_guarantee</code> element is the guaranteed
 	minimum memory allocation for the guest. The units for this value are
 	kilobytes (i.e. blocks of 1024 bytes)</dd>
+      <dt><code>cputune</code></dt>
+      <dd> The optional <code>cputune</code> element provides details
+      regarding the cpu tuneable parameters for the domain. If this is
+      omitted, it defaults to the OS provided defaults.</dd>
+      <dt><code>shares</code></dt>
+      <dd> The optional <code>shares</code> element is the proportional
+      weighted share for the domain. If this is omitted, it defaults to the OS
+      provided defaults.</dd>
       <dt><code>vcpu</code></dt>
       <dd>The content of this element defines the maximum number of virtual
         CPUs allocated for the guest OS, which must be between 1 and
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 645767e..63c8927 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -4904,6 +4904,11 @@ static virDomainDefPtr virDomainDefParseXML(virCapsPtr caps,
                       &def->mem.swap_hard_limit) < 0)
         def->mem.swap_hard_limit = 0;
 
+    /* Extract cpu tunables */
+    if (virXPathULong("string(./cputune/shares[1])", ctxt,
+                      &def->cputune.shares) < 0)
+        def->cputune.shares = 0;
+
     n = virXPathULong("string(./vcpu[1])", ctxt, &count);
     if (n == -2) {
         virDomainReportError(VIR_ERR_XML_ERROR, "%s",
@@ -7313,6 +7318,15 @@ char *virDomainDefFormat(virDomainDefPtr def,
         def->mem.swap_hard_limit)
         virBufferVSprintf(&buf, "  </memtune>\n");
 
+    if (def->cputune.shares)
+        virBufferVSprintf(&buf, "  <cputune>\n");
+    if (def->cputune.shares) {
+        virBufferVSprintf(&buf, "    <shares>%lu</shares>\n",
+                          def->cputune.shares);
+    }
+    if (def->cputune.shares)
+        virBufferVSprintf(&buf, "  </cputune>\n");
+
     if (def->mem.hugepage_backed) {
         virBufferAddLit(&buf, "  <memoryBacking>\n");
         virBufferAddLit(&buf, "    <hugepages/>\n");
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index cf7bdc0..a2c83d3 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -981,6 +981,9 @@ struct _virDomainDef {
     unsigned short maxvcpus;
     int cpumasklen;
     char *cpumask;
+    struct {
+        unsigned long shares; /* proportional weight */
+    } cputune;
 
     /* These 3 are based on virDomainLifeCycleAction enum flags */
     int onReboot;
diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
index af0b70c..24edb49 100644
--- a/src/lxc/lxc_controller.c
+++ b/src/lxc/lxc_controller.c
@@ -144,6 +144,16 @@ static int lxcSetContainerResources(virDomainDefPtr def)
         }
     }
 
+    if(def->cputune.shares) {
+        rc = virCgroupSetCpuShares(cgroup, def->cputune.shares);
+        if (rc != 0) {
+            virReportSystemError(-rc,
+                                 _("Unable to set cpu shares for domain %s"),
+                                 def->name);
+            goto cleanup;
+        }
+    }
+
     rc = virCgroupDenyAllDevices(cgroup);
     if (rc != 0) {
         virReportSystemError(-rc,
diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
index e5536c0..d4e73bd 100644
--- a/src/qemu/qemu_cgroup.c
+++ b/src/qemu/qemu_cgroup.c
@@ -304,6 +304,21 @@ int qemuSetupCgroup(struct qemud_driver *driver,
                  vm->def->name);
     }
 
+    if ((rc = qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU))) {
+        if (vm->def->cputune.shares != 0) {
+            rc = virCgroupSetCpuShares(cgroup, vm->def->cputune.shares);
+            if (rc != 0) {
+                virReportSystemError(-rc,
+                                     _("Unable to set cpu shares for domain %s"),
+                                     vm->def->name);
+                goto cleanup;
+            }
+        }
+    } else {
+        VIR_WARN("CPU cgroup is disabled in qemu configuration file: %s",
+                 vm->def->name);
+    }
+
 done:
     virCgroupFree(&cgroup);
     return 0;