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[PATCH 5/5] blkiotune: add qemu support for blkiotune.device_weight

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Implement setting/getting per-device blkio weights in qemu,
using the cgroups blkio.weight_device tunable.

---
 src/libvirt_private.syms |    1 +
 src/qemu/qemu_cgroup.c   |   22 +++++
 src/qemu/qemu_driver.c   |  216 ++++++++++++++++++++++++++++++++++++++++++++-
 src/util/cgroup.c        |   20 ++++
 src/util/cgroup.h        |    3 +
 5 files changed, 257 insertions(+), 5 deletions(-)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index f7d0fb2..b32d5de 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -89,6 +89,7 @@ virCgroupKillRecursive;
 virCgroupMounted;
 virCgroupPathOfController;
 virCgroupRemove;
+virCgroupSetBlkioDeviceWeight;
 virCgroupSetBlkioWeight;
 virCgroupSetCpuShares;
 virCgroupSetCpuCfsPeriod;
diff --git a/src/qemu/qemu_cgroup.c b/src/qemu/qemu_cgroup.c
index 2a10bd2..d397578 100644
--- a/src/qemu/qemu_cgroup.c
+++ b/src/qemu/qemu_cgroup.c
@@ -312,6 +312,28 @@ int qemuSetupCgroup(struct qemud_driver *driver,
         }
     }
 
+    if (qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_BLKIO)) {
+        char *tmp;
+        if (virBlkioDeviceWeightToStr(vm->def->blkio.devices,
+                                      vm->def->blkio.ndevices,
+                                      &tmp) < 0) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("Unable to set io device weight for domain %s"),
+                            vm->def->name);
+            goto cleanup;
+        }
+        if (tmp) {
+            rc = virCgroupSetBlkioDeviceWeight(cgroup, tmp);
+            VIR_FREE(tmp);
+            if (rc != 0) {
+                virReportSystemError(-rc,
+                                     _("Unable to set io device weight for domain %s"),
+                                     vm->def->name);
+                goto cleanup;
+            }
+        }
+    }
+
     if (vm->def->mem.hard_limit != 0 ||
         vm->def->mem.soft_limit != 0 ||
         vm->def->mem.swap_hard_limit != 0) {
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c8a858e..40568d0 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -112,7 +112,7 @@
 # define KVM_CAP_NR_VCPUS 9       /* returns max vcpus per vm */
 #endif
 
-#define QEMU_NB_BLKIO_PARAM  1
+#define QEMU_NB_BLKIO_PARAM  2
 
 static void processWatchdogEvent(void *data, void *opaque);
 
@@ -5888,6 +5888,86 @@ cleanup:
     return ret;
 }
 
+/* deviceWeightStr in the form of /device/path,weight,/device/path,weight
+ * for example, /dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0,800
+ */
+static int
+parseBlkioWeightDeviceStr(char *deviceWeightStr,
+                          virBlkioDeviceWeightPtr *dw, int *size)
+{
+    char *temp;
+    int ndevices = 0;
+    int nsep = 0;
+    int i;
+    virBlkioDeviceWeightPtr result = NULL;
+
+    temp = deviceWeightStr;
+    while (temp) {
+        temp = strchr(temp, ',');
+        if (temp) {
+            temp++;
+            nsep++;
+        }
+    }
+
+    /* a valid string must have even number of fields */
+    if (!(nsep & 1))
+        goto error;
+
+    ndevices = (nsep + 1) / 2;
+
+    if (VIR_ALLOC_N(result, ndevices) < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    i = 0;
+    temp = deviceWeightStr;
+    while (temp && i < ndevices) {
+        char *p = temp;
+
+        /* device path */
+
+        p = strchr(p, ',');
+        if (!p)
+            goto error;
+
+        result[i].path = strndup(temp, p - temp);
+        if (!result[i].path) {
+            virReportOOMError();
+            goto cleanup;
+        }
+
+        /* weight */
+        temp = p + 1;
+
+        if (virStrToLong_ui(temp, &p, 10, &result[i].weight) < 0)
+            goto error;
+
+        i++;
+        if (*p == '\0')
+            break;
+        else if (*p != ',')
+            goto error;
+        temp = p + 1;
+    }
+    if (i != ndevices)
+        goto error;
+
+    *dw = result;
+    *size = i;
+
+    return 0;
+
+error:
+    qemuReportError(VIR_ERR_INVALID_ARG,
+                    _("unable to parse %s"), deviceWeightStr);
+cleanup:
+    virBlkioDeviceWeightArrayClear(result, ndevices);
+    VIR_FREE(result);
+    return -1;
+}
+
 static int qemuDomainSetBlkioParameters(virDomainPtr dom,
                                          virTypedParameterPtr params,
                                          int nparams,
@@ -5954,10 +6034,10 @@ static int qemuDomainSetBlkioParameters(virDomainPtr dom,
     ret = 0;
     if (flags & VIR_DOMAIN_AFFECT_LIVE) {
         for (i = 0; i < nparams; i++) {
+            int rc;
             virTypedParameterPtr param = &params[i];
 
             if (STREQ(param->field, VIR_DOMAIN_BLKIO_WEIGHT)) {
-                int rc;
                 if (param->type != VIR_TYPED_PARAM_UINT) {
                     qemuReportError(VIR_ERR_INVALID_ARG, "%s",
                                     _("invalid type for blkio weight tunable, expected a 'unsigned int'"));
@@ -5978,6 +6058,53 @@ static int qemuDomainSetBlkioParameters(virDomainPtr dom,
                                          _("unable to set blkio weight tunable"));
                     ret = -1;
                 }
+            } else if (STREQ(param->field, VIR_DOMAIN_BLKIO_DEVICE_WEIGHT)) {
+                int ndevices;
+                virBlkioDeviceWeightPtr devices = NULL;
+                char *tmp;
+                if (param->type != VIR_TYPED_PARAM_STRING) {
+                    qemuReportError(VIR_ERR_INVALID_ARG, "%s",
+                                    _("invalid type for device_weight tunable, expected a 'char *'"));
+                    ret = -1;
+                    continue;
+                }
+
+                if (parseBlkioWeightDeviceStr(params[i].value.s,
+                                              &devices,
+                                              &ndevices) < 0) {
+                    ret = -1;
+                    continue;
+                }
+                if (virBlkioDeviceWeightToStr(devices,
+                                              ndevices,
+                                              &tmp) < 0) {
+                    qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                                    _("Unable to set blkio weight_device tunable"));
+                    virBlkioDeviceWeightArrayClear(devices, ndevices);
+                    VIR_FREE(devices);
+                    ret = -1;
+                    continue;
+                }
+                if (tmp) {
+                    rc = virCgroupSetBlkioDeviceWeight(group, tmp);
+                    VIR_FREE(tmp);
+                    if (rc != 0) {
+                            virReportSystemError(-rc, "%s",
+                                                 _("unable to set blkio weight_device tunable"));
+                            ret = -1;
+                            virBlkioDeviceWeightArrayClear(devices, ndevices);
+                            VIR_FREE(devices);
+                            continue;
+                    }
+                    virBlkioDeviceWeightArrayClear(vm->def->blkio.devices,
+                                                   vm->def->blkio.ndevices);
+                    VIR_FREE(vm->def->blkio.devices);
+                    vm->def->blkio.devices = devices;
+                    vm->def->blkio.ndevices = ndevices;
+                } else {
+                    virBlkioDeviceWeightArrayClear(devices, ndevices);
+                    VIR_FREE(devices);
+                }
             } else {
                 qemuReportError(VIR_ERR_INVALID_ARG,
                                 _("Parameter `%s' not supported"), param->field);
@@ -6007,9 +6134,24 @@ static int qemuDomainSetBlkioParameters(virDomainPtr dom,
                 }
 
                 persistentDef->blkio.weight = params[i].value.ui;
+            } else if (STREQ(param->field, VIR_DOMAIN_BLKIO_DEVICE_WEIGHT)) {
+                virBlkioDeviceWeightPtr devices = NULL;
+                int ndevices;
+                if (parseBlkioWeightDeviceStr(params[i].value.s,
+                                              &devices,
+                                              &ndevices) < 0) {
+                    ret = -1;
+                    continue;
+                }
+                virBlkioDeviceWeightArrayClear(persistentDef->blkio.devices,
+                                               persistentDef->blkio.ndevices);
+                VIR_FREE(persistentDef->blkio.devices);
+                persistentDef->blkio.devices = devices;
+                persistentDef->blkio.ndevices = ndevices;
             } else {
                 qemuReportError(VIR_ERR_INVALID_ARG,
-                                _("Parameter `%s' not supported"), param->field);
+                                _("Parameter `%s' not supported"),
+                                param->field);
                 ret = -1;
             }
         }
@@ -6032,7 +6174,7 @@ static int qemuDomainGetBlkioParameters(virDomainPtr dom,
                                          unsigned int flags)
 {
     struct qemud_driver *driver = dom->conn->privateData;
-    int i;
+    int i, j;
     virCgroupPtr group = NULL;
     virDomainObjPtr vm = NULL;
     virDomainDefPtr persistentDef = NULL;
@@ -6046,7 +6188,8 @@ static int qemuDomainGetBlkioParameters(virDomainPtr dom,
                   VIR_TYPED_PARAM_STRING_OKAY, -1);
     qemuDriverLock(driver);
 
-    /* We don't return strings, and thus trivially support this flag.  */
+    /* We blindly return a string, and let libvirt.c do the filtering
+     * on behalf of older clients that can't parse it.  */
     flags &= ~VIR_TYPED_PARAM_STRING_OKAY;
 
     vm = virDomainFindByUUID(&driver->domains, dom->uuid);
@@ -6125,6 +6268,37 @@ static int qemuDomainGetBlkioParameters(virDomainPtr dom,
                 }
                 param->value.ui = val;
                 break;
+            case 1: /* blkiotune.device_weight */
+                if (vm->def->blkio.ndevices > 0) {
+                    virBuffer buf = VIR_BUFFER_INITIALIZER;
+                    for (j = 0; j < vm->def->blkio.ndevices; j++) {
+                        if (j)
+                            virBufferAddChar(&buf, ',');
+                        virBufferAsprintf(&buf, "%s,%u",
+                                          vm->def->blkio.devices[j].path,
+                                          vm->def->blkio.devices[j].weight);
+                    }
+                    if (virBufferError(&buf)) {
+                        virReportOOMError();
+                        goto cleanup;
+                    }
+                    param->value.s = virBufferContentAndReset(&buf);
+                } else {
+                    param->value.s = strdup("");
+                    if (!param->value.s) {
+                        virReportOOMError();
+                        goto cleanup;
+                    }
+                }
+                param->type = VIR_TYPED_PARAM_STRING;
+                if (virStrcpyStatic(param->field,
+                                    VIR_DOMAIN_BLKIO_DEVICE_WEIGHT) == NULL) {
+                    qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                                    _("Field name '%s' too long"),
+                                    VIR_DOMAIN_BLKIO_DEVICE_WEIGHT);
+                    goto cleanup;
+                }
+                break;
 
             default:
                 break;
@@ -6149,6 +6323,38 @@ static int qemuDomainGetBlkioParameters(virDomainPtr dom,
                 param->value.ui = persistentDef->blkio.weight;
                 break;
 
+            case 1: /* blkiotune.device_weight */
+                if (persistentDef->blkio.ndevices > 0) {
+                    virBuffer buf = VIR_BUFFER_INITIALIZER;
+                    for (j = 0; j < persistentDef->blkio.ndevices; j++) {
+                        if (j)
+                            virBufferAddChar(&buf, ',');
+                        virBufferAsprintf(&buf, "%s,%u",
+                                          persistentDef->blkio.devices[j].path,
+                                          persistentDef->blkio.devices[j].weight);
+                    }
+                    if (virBufferError(&buf)) {
+                        virReportOOMError();
+                        goto cleanup;
+                    }
+                    param->value.s = virBufferContentAndReset(&buf);
+                } else {
+                    param->value.s = strdup("");
+                    if (!param->value.s) {
+                        virReportOOMError();
+                        goto cleanup;
+                    }
+                }
+                param->type = VIR_TYPED_PARAM_STRING;
+                if (virStrcpyStatic(param->field,
+                                    VIR_DOMAIN_BLKIO_DEVICE_WEIGHT) == NULL) {
+                    qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                                    _("Field name '%s' too long"),
+                                    VIR_DOMAIN_BLKIO_DEVICE_WEIGHT);
+                    goto cleanup;
+                }
+                break;
+
             default:
                 break;
                 /* should not hit here */
diff --git a/src/util/cgroup.c b/src/util/cgroup.c
index c8d1f33..b510640 100644
--- a/src/util/cgroup.c
+++ b/src/util/cgroup.c
@@ -982,6 +982,26 @@ int virCgroupGetBlkioWeight(virCgroupPtr group, unsigned int *weight)
 }
 
 /**
+ * virCgroupSetBlkioDeviceWeight:
+ *
+ * @group: The cgroup to change io device weight device for
+ * @device_weight: The device weight for this cgroup
+ *
+ * device_weight is treated as a write-only parameter, so
+ * there isn't a getter counterpart.
+ *
+ * Returns: 0 on success
+ */
+int virCgroupSetBlkioDeviceWeight(virCgroupPtr group,
+                                  const char *device_weight)
+{
+    return virCgroupSetValueStr(group,
+                                VIR_CGROUP_CONTROLLER_BLKIO,
+                                "blkio.weight_device",
+                                device_weight);
+}
+
+/**
  * virCgroupSetMemory:
  *
  * @group: The cgroup to change memory for
diff --git a/src/util/cgroup.h b/src/util/cgroup.h
index d190bb3..9972671 100644
--- a/src/util/cgroup.h
+++ b/src/util/cgroup.h
@@ -55,6 +55,9 @@ int virCgroupAddTask(virCgroupPtr group, pid_t pid);
 int virCgroupSetBlkioWeight(virCgroupPtr group, unsigned int weight);
 int virCgroupGetBlkioWeight(virCgroupPtr group, unsigned int *weight);
 
+int virCgroupSetBlkioDeviceWeight(virCgroupPtr group,
+                                  const char *device_weight);
+
 int virCgroupSetMemory(virCgroupPtr group, unsigned long long kb);
 int virCgroupGetMemoryUsage(virCgroupPtr group, unsigned long *kb);
 
-- 
1.7.3.1

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