Re: [libvirt] PATCH: 2/3: Implement schedular params for QEMU

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

This patch implements the schedular parameter APIs. This adds a
single tunable 'cpu_shares' that is provided by cgroups. This is
a slightly more fancy way of doing nice priorities, giving a way
to tune relative priority of  VMs

Daniel

diff --git a/src/qemu_driver.c b/src/qemu_driver.c
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -3844,6 +3844,111 @@ cleanup:
     return ret;
 }
 
+
+static char *qemuGetSchedulerType(virDomainPtr domain ATTRIBUTE_UNUSED,
+                                 int *nparams)
+{
+    if (nparams)
+        *nparams = 1;
+
+    return strdup("posix");
+}
+
+static int qemuSetSchedulerParameters(virDomainPtr domain,
+                                     virSchedParameterPtr params,
+                                     int nparams)
+{
+    struct qemud_driver *driver = domain->conn->privateData;
+    int i;
+    virCgroupPtr group = NULL;
+    virDomainObjPtr vm = NULL;
+    int ret = -1;
+
+    if (virCgroupHaveSupport() != 0)
+        return -1;
+
+    qemuDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, domain->uuid);
+    qemuDriverUnlock(driver);
+
+    if (vm == NULL) {
+        qemudReportError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
+                         _("No such domain %s"), domain->uuid);
+        goto cleanup;
+    }
+
+    if (virCgroupForDomain(vm->def, "qemu", &group) != 0)
+        goto cleanup;
+
+    for (i = 0; i < nparams; i++) {
+        virSchedParameterPtr param = &params[i];
+
+        if (STREQ(param->field, "cpu_shares")) {
+            if (virCgroupSetCpuShares(group, params[i].value.ui) != 0)
+                goto cleanup;
+        } else {
+            qemudReportError(domain->conn, domain, NULL, VIR_ERR_INVALID_ARG,
+                             _("Invalid parameter `%s'"), param->field);
+            goto cleanup;
+        }
+    }
+    ret = 0;
+
+cleanup:
+    virCgroupFree(&group);
+    if (vm)
+        virDomainObjUnlock(vm);
+    return ret;
+}
+
+static int qemuGetSchedulerParameters(virDomainPtr domain,
+                                     virSchedParameterPtr params,
+                                     int *nparams)
+{
+    struct qemud_driver *driver = domain->conn->privateData;
+    virCgroupPtr group = NULL;
+    virDomainObjPtr vm = NULL;
+    unsigned long val;
+    int ret = -1;
+
+    if (virCgroupHaveSupport() != 0)
+        return -1;
+
+    if ((*nparams) != 1) {
+        qemudReportError(domain->conn, domain, NULL, VIR_ERR_INVALID_ARG,
+                         "%s", _("Invalid parameter count"));
+        return -1;
+    }
+
+    qemuDriverLock(driver);
+    vm = virDomainFindByUUID(&driver->domains, domain->uuid);
+    qemuDriverUnlock(driver);
+
+    if (vm == NULL) {
+        qemudReportError(domain->conn, domain, NULL, VIR_ERR_INTERNAL_ERROR,
+                         _("No such domain %s"), domain->uuid);
+        goto cleanup;
+    }
+
+    if (virCgroupForDomain(vm->def, "qemu", &group) != 0)
+        goto cleanup;
+
+    if (virCgroupGetCpuShares(group, &val) != 0)
+        goto cleanup;
+    params[0].value.ul = val;
+    strncpy(params[0].field, "cpu_shares", sizeof(params[0].field));
+    params[0].type = VIR_DOMAIN_SCHED_FIELD_ULLONG;
+
+    ret = 0;
+
+cleanup:
+    virCgroupFree(&group);
+    if (vm)
+        virDomainObjUnlock(vm);
+    return ret;
+}
+
+
 /* This uses the 'info blockstats' monitor command which was
  * integrated into both qemu & kvm in late 2007.  If the command is
  * not supported we detect this and return the appropriate error.
@@ -4650,9 +4755,9 @@ static virDriver qemuDriver = {
     qemudDomainDetachDevice, /* domainDetachDevice */
     qemudDomainGetAutostart, /* domainGetAutostart */
     qemudDomainSetAutostart, /* domainSetAutostart */
-    NULL, /* domainGetSchedulerType */
-    NULL, /* domainGetSchedulerParameters */
-    NULL, /* domainSetSchedulerParameters */
+    qemuGetSchedulerType, /* domainGetSchedulerType */
+    qemuGetSchedulerParameters, /* domainGetSchedulerParameters */
+    qemuSetSchedulerParameters, /* domainSetSchedulerParameters */
     NULL, /* domainMigratePrepare (v1) */
     qemudDomainMigratePerform, /* domainMigratePerform */
     NULL, /* domainMigrateFinish */

-- 
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