conf: Make scheduler formatting simpler

Since the great rework of how we store vcpu- and iothread-related
data, we have overly complex part of code that is trying to format the
scheduler tuning data in as less lines as possible by grouping
settings for multiple threads.  That was designed as an input syntax
sugar for users, but we don't need to also use that when formatting
the XML.  Switching to simple enumeration makes the code nicer,
shorter and more welcoming to future changes.
Signed-off-by: NMartin Kletzander <mkletzan@redhat.com>

src/conf/domain_conf.c

@@ -23294,183 +23294,35 @@ virDomainDefHasCapabilitiesFeatures(virDomainDefPtr def)
 }
 
 
-/**
- * virDomainFormatSchedDef:
- * @def: domain definiton
- * @buf: target XML buffer
- * @name: name of the target XML element
- * @func: function that returns the thread scheduler parameter struct for an object
- * @resourceMap: bitmap of indexes of objects that shall be formatted (used with @func)
- *
- * Formats one of the two scheduler tuning elements to the XML. This function
- * transforms the internal representation where the scheduler info is stored
- * per-object to the XML representation where the info is stored per group of
- * objects. This function autogroups all the relevant scheduler configs.
- *
- * Returns 0 on success -1 on error.
- */
-static int
-virDomainFormatSchedDef(virDomainDefPtr def,
-                        virBufferPtr buf,
-                        const char *name,
-                        virDomainThreadSchedParamPtr (*func)(virDomainDefPtr, unsigned int),
-                        virBitmapPtr resourceMap)
-{
-    virBitmapPtr schedMap = NULL;
-    virBitmapPtr prioMap = NULL;
-    virDomainThreadSchedParamPtr sched;
-    char *tmp = NULL;
-    ssize_t next;
-    size_t i;
-    int ret = -1;
-
-    /* Okay, @func should never return NULL here because it does
-     * so iff corresponding resource does not exists. But if it
-     * doesn't we should not have been called in the first place.
-     * But some compilers fails to see this complex reasoning and
-     * deduct that this code is buggy. Shut them up by checking
-     * for return value of sched. Even though we don't need to.
-     */
-
-    if (!(schedMap = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN)) ||
-        !(prioMap = virBitmapNew(VIR_DOMAIN_CPUMASK_LEN)))
-        goto cleanup;
-
-    for (i = VIR_PROC_POLICY_NONE + 1; i < VIR_PROC_POLICY_LAST; i++) {
-        virBitmapClearAll(schedMap);
-
-        /* find vcpus using a particular scheduler */
-        next = -1;
-        while ((next = virBitmapNextSetBit(resourceMap, next)) > -1) {
-            sched = func(def, next);
-
-            if (sched && sched->policy == i)
-                ignore_value(virBitmapSetBit(schedMap, next));
-        }
-
-        /* it's necessary to discriminate priority levels for schedulers that
-         * have them */
-        while (!virBitmapIsAllClear(schedMap)) {
-            virBitmapPtr currentMap = NULL;
-            ssize_t nextprio;
-            bool hasPriority = false;
-            int priority = 0;
-
-            switch ((virProcessSchedPolicy) i) {
-            case VIR_PROC_POLICY_NONE:
-            case VIR_PROC_POLICY_BATCH:
-            case VIR_PROC_POLICY_IDLE:
-            case VIR_PROC_POLICY_LAST:
-                currentMap = schedMap;
-                break;
-
-            case VIR_PROC_POLICY_FIFO:
-            case VIR_PROC_POLICY_RR:
-                virBitmapClearAll(prioMap);
-                hasPriority = true;
-
-                /* we need to find a subset of vCPUs with the given scheduler
-                 * that share the priority */
-                nextprio = virBitmapNextSetBit(schedMap, -1);
-                if (!(sched = func(def, nextprio)))
-                    goto cleanup;
-
-                priority = sched->priority;
-                ignore_value(virBitmapSetBit(prioMap, nextprio));
-
-                while ((nextprio = virBitmapNextSetBit(schedMap, nextprio)) > -1) {
-                    sched = func(def, nextprio);
-                    if (sched && sched->priority == priority)
-                        ignore_value(virBitmapSetBit(prioMap, nextprio));
-                }
-
-                currentMap = prioMap;
-                break;
-            }
-
-            /* now we have the complete group */
-            if (!(tmp = virBitmapFormat(currentMap)))
-                goto cleanup;
-
-            virBufferAsprintf(buf,
-                              "<%sched %s='%s' scheduler='%s'",
-                              name, name, tmp,
-                              virProcessSchedPolicyTypeToString(i));
-            VIR_FREE(tmp);
-
-            if (hasPriority)
-                virBufferAsprintf(buf, " priority='%d'", priority);
+static void
+virDomainSchedulerFormat(virBufferPtr buf,
+                         const char *name,
+                         virDomainThreadSchedParamPtr sched,
+                         size_t id)
+{
+    switch (sched->policy) {
+        case VIR_PROC_POLICY_BATCH:
+        case VIR_PROC_POLICY_IDLE:
+            virBufferAsprintf(buf, "<%ssched "
+                              "%ss='%zu' scheduler='%s'/>\n",
+                              name, name, id,
+                              virProcessSchedPolicyTypeToString(sched->policy));
+            break;
 
-            virBufferAddLit(buf, "/>\n");
+        case VIR_PROC_POLICY_RR:
+        case VIR_PROC_POLICY_FIFO:
+            virBufferAsprintf(buf, "<%ssched "
+                              "%ss='%zu' scheduler='%s' priority='%d'/>\n",
+                              name, name, id,
+                              virProcessSchedPolicyTypeToString(sched->policy),
+                              sched->priority);
+            break;
 
-            /* subtract all vCPUs that were already found */
-            virBitmapSubtract(schedMap, currentMap);
+        case VIR_PROC_POLICY_NONE:
+        case VIR_PROC_POLICY_LAST:
+            break;
         }
-    }
-
-    ret = 0;
-
- cleanup:
-    virBitmapFree(schedMap);
-    virBitmapFree(prioMap);
-    return ret;
-}
-
-
-static int
-virDomainFormatVcpuSchedDef(virDomainDefPtr def,
-                            virBufferPtr buf)
-{
-    virBitmapPtr allcpumap;
-    int ret;
-
-    if (virDomainDefGetVcpusMax(def) == 0)
-        return 0;
-
-    if (!(allcpumap = virBitmapNew(virDomainDefGetVcpusMax(def))))
-        return -1;
-
-    virBitmapSetAll(allcpumap);
-
-    ret = virDomainFormatSchedDef(def, buf, "vcpus", virDomainDefGetVcpuSched,
-                                  allcpumap);
-
-    virBitmapFree(allcpumap);
-    return ret;
-}
-
-
-static int
-virDomainFormatIOThreadSchedDef(virDomainDefPtr def,
-                                virBufferPtr buf)
-{
-    virBitmapPtr threadmap;
-    size_t i;
-    int ret = -1;
-
-    if (def->niothreadids == 0)
-        return 0;
-
-    if (!(threadmap = virBitmapNewEmpty()))
-        return -1;
 
-    for (i = 0; i < def->niothreadids; i++) {
-        if (def->iothreadids[i]->sched.policy != VIR_PROC_POLICY_NONE &&
-            virBitmapSetBitExpand(threadmap, def->iothreadids[i]->iothread_id) < 0)
-            goto cleanup;
-    }
-
-    if (virBitmapIsAllClear(threadmap)) {
-        ret = 0;
-        goto cleanup;
-    }
-
-    ret = virDomainFormatSchedDef(def, buf, "iothreads",
-                                  virDomainDefGetIOThreadSched, threadmap);
-
- cleanup:
-    virBitmapFree(threadmap);
-    return ret;
 }
 
 
@@ -23564,11 +23416,16 @@ virDomainCputuneDefFormat(virBufferPtr buf,
         VIR_FREE(cpumask);
     }
 
-    if (virDomainFormatVcpuSchedDef(def, &childrenBuf) < 0)
-        goto cleanup;
+    for (i = 0; i < def->maxvcpus; i++) {
+        virDomainSchedulerFormat(&childrenBuf, "vcpu",
+                                 &def->vcpus[i]->sched, i);
+    }
 
-    if (virDomainFormatIOThreadSchedDef(def, &childrenBuf) < 0)
-        goto cleanup;
+    for (i = 0; i < def->niothreadids; i++) {
+        virDomainSchedulerFormat(&childrenBuf, "iothread",
+                                 &def->iothreadids[i]->sched,
+                                 def->iothreadids[i]->iothread_id);
+    }
 
     if (virBufferUse(&childrenBuf)) {
         virBufferAddLit(buf, "<cputune>\n");

tests/qemuxml2xmloutdata/qemuxml2xmlout-cputune-iothreadsched-zeropriority.xml

@@ -12,8 +12,11 @@
     <vcpupin vcpu='0' cpuset='0'/>
     <vcpupin vcpu='1' cpuset='1'/>
     <emulatorpin cpuset='1'/>
-    <vcpusched vcpus='0-1' scheduler='fifo' priority='0'/>
-    <iothreadsched iothreads='1-3' scheduler='rr' priority='0'/>
+    <vcpusched vcpus='0' scheduler='fifo' priority='0'/>
+    <vcpusched vcpus='1' scheduler='fifo' priority='0'/>
+    <iothreadsched iothreads='1' scheduler='rr' priority='0'/>
+    <iothreadsched iothreads='2' scheduler='rr' priority='0'/>
+    <iothreadsched iothreads='3' scheduler='rr' priority='0'/>
   </cputune>
   <os>
     <type arch='i686' machine='pc'>hvm</type>

tests/qemuxml2xmloutdata/qemuxml2xmlout-cputune-iothreadsched.xml

@@ -12,8 +12,11 @@
     <vcpupin vcpu='0' cpuset='0'/>
     <vcpupin vcpu='1' cpuset='1'/>
     <emulatorpin cpuset='1'/>
-    <vcpusched vcpus='0-1' scheduler='fifo' priority='1'/>
-    <iothreadsched iothreads='1-3' scheduler='batch'/>
+    <vcpusched vcpus='0' scheduler='fifo' priority='1'/>
+    <vcpusched vcpus='1' scheduler='fifo' priority='1'/>
+    <iothreadsched iothreads='1' scheduler='batch'/>
+    <iothreadsched iothreads='2' scheduler='batch'/>
+    <iothreadsched iothreads='3' scheduler='batch'/>
   </cputune>
   <os>
     <type arch='i686' machine='pc'>hvm</type>