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[libvirt] [PATCH v6 1/4] numa: describe siblings distances within cells



From: Wim ten Have <wim ten have oracle com>

Add support for describing NUMA distances in a domain's <numa> <cell>
XML description.

Below is an example of a 4 node setup:

  <cpu>
    <numa>
      <cell id='0' cpus='0-3' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='10'/>
          <sibling id='1' value='21'/>
          <sibling id='2' value='31'/>
          <sibling id='3' value='21'/>
        </distances>
      </cell>
      <cell id='1' cpus='4-7' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='21'/>
          <sibling id='1' value='10'/>
          <sibling id='2' value='21'/>
          <sibling id='3' value='31'/>
        </distances>
      </cell>
      <cell id='2' cpus='8-11' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='31'/>
          <sibling id='1' value='21'/>
          <sibling id='2' value='10'/>
          <sibling id='3' value='21'/>
        </distances>
      <cell id='3' cpus='12-15' memory='2097152' unit='KiB'>
        <distances>
          <sibling id='0' value='21'/>
          <sibling id='1' value='31'/>
          <sibling id='2' value='21'/>
          <sibling id='3' value='10'/>
        </distances>
      </cell>
    </numa>
  </cpu>

A <cell> defines a NUMA node. <distances> describes the NUMA distance
from the <cell> to the other NUMA nodes (the <sibling>s).  For example,
in above XML description, the distance between NUMA node0 <cell id='0'
...> and NUMA node2 <sibling id='2' ...> is 31.

Valid distance value are '10 <= value <= 255'.  A distance value of 10
represents the distance to the node itself.  A distance value of 20
represents the default value for remote nodes but other values are
possible depending on the physical topology of the system.

When distances are not fully described, any missing sibling distance
values will default to 10 for local nodes and 20 for remote nodes.

If distance is given for A -> B, then we default B -> A to the same
value instead of 20.

Signed-off-by: Wim ten Have <wim ten have oracle com>
Reviewed-by: Daniel P. Berrange <berrange redhat com>
---
Changes on v1:
- Add changes to docs/formatdomain.html.in describing schema update.
Changes on v2:
- Automatically apply distance symmetry maintaining cell <-> sibling.
- Check for maximum '255' on numaDistanceValue.
- Automatically complete empty distance ranges.
- Check that sibling_id's are in range with cell identifiers.
- Allow non-contiguous ranges, starting from any node id.
- Respect parameters as ATTRIBUTE_NONNULL fix functions and callers.
- Add and apply topology for LOCAL_DISTANCE=10 and REMOTE_DISTANCE=20.
Changes on v3:
- Add UNREACHABLE if one locality is unreachable from another.
- Add code cleanup aligning function naming in a separated patch.
- Add numa related driver code in a separated patch.
- Remove <choice> from numaDistanceValue schema/basictypes.rng
- Correct doc changes.
Changes on v4:
- Fix symmetry error under virDomainNumaDefNodeDistanceParseXML()
Changes on v5:
- Apply doc suggestions.
- Apply virReportError() message suggestions.
- Remove redundant sanity checks from virDomainNumaDefNodeDistanceParseXML().
---
 docs/formatdomain.html.in   |  63 ++++++++++++++-
 docs/schemas/basictypes.rng |   7 ++
 docs/schemas/cputypes.rng   |  18 +++++
 src/conf/numa_conf.c        | 191 +++++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 275 insertions(+), 4 deletions(-)

diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 4f28dce35..df2f17f5d 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1529,7 +1529,68 @@
     </p>
 
     <p>
-      This guest NUMA specification is currently available only for QEMU/KVM.
+      This guest NUMA specification is currently available only for
+      QEMU/KVM and Xen.  Whereas Xen driver also allows for a distinct
+      description of NUMA arranged <code>sibling</code> <code>cell</code>
+      <code>distances</code> <span class="since">Since 3.9.0</span>.
+    </p>
+
+    <p>
+      Under NUMA hardware architecture, distinct resources such as memory
+      create a designated distance between <code>cell</code> and
+      <code>siblings</code> that now can be described with the help of
+      <code>distances</code>. A detailed description can be found within
+      the ACPI (Advanced Configuration and Power Interface Specification)
+      within the chapter explaining the system's SLIT (System Locality
+      Distance Information Table).
+    </p>
+
+<pre>
+...
+&lt;cpu&gt;
+  ...
+  &lt;numa&gt;
+    &lt;cell id='0' cpus='0,4-7' memory='512000' unit='KiB'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='10'/&gt;
+        &lt;sibling id='1' value='21'/&gt;
+        &lt;sibling id='2' value='31'/&gt;
+        &lt;sibling id='3' value='41'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='1' cpus='1,8-10,12-15' memory='512000' unit='KiB' memAccess='shared'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='21'/&gt;
+        &lt;sibling id='1' value='10'/&gt;
+        &lt;sibling id='2' value='21'/&gt;
+        &lt;sibling id='3' value='31'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='2' cpus='2,11' memory='512000' unit='KiB' memAccess='shared'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='31'/&gt;
+        &lt;sibling id='1' value='21'/&gt;
+        &lt;sibling id='2' value='10'/&gt;
+        &lt;sibling id='3' value='21'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+    &lt;cell id='3' cpus='3' memory='512000' unit='KiB'&gt;
+      &lt;distances&gt;
+        &lt;sibling id='0' value='41'/&gt;
+        &lt;sibling id='1' value='31'/&gt;
+        &lt;sibling id='2' value='21'/&gt;
+        &lt;sibling id='3' value='10'/&gt;
+      &lt;/distances&gt;
+    &lt;/cell&gt;
+  &lt;/numa&gt;
+  ...
+&lt;/cpu&gt;
+...</pre>
+
+    <p>
+      Under Xen driver, if no <code>distances</code> are given to describe
+      the SLIT data between different cells, it will default to a scheme
+      using 10 for local and 20 for remote distances.
     </p>
 
     <h3><a id="elementsEvents">Events configuration</a></h3>
diff --git a/docs/schemas/basictypes.rng b/docs/schemas/basictypes.rng
index 1ea667cdf..1a18cd31b 100644
--- a/docs/schemas/basictypes.rng
+++ b/docs/schemas/basictypes.rng
@@ -77,6 +77,13 @@
     </choice>
   </define>
 
+  <define name="numaDistanceValue">
+    <data type="unsignedInt">
+      <param name="minInclusive">10</param>
+      <param name="maxInclusive">255</param>
+    </data>
+  </define>
+
   <define name="pciaddress">
     <optional>
       <attribute name="domain">
diff --git a/docs/schemas/cputypes.rng b/docs/schemas/cputypes.rng
index 3eef16abc..c45b6dfb2 100644
--- a/docs/schemas/cputypes.rng
+++ b/docs/schemas/cputypes.rng
@@ -129,6 +129,24 @@
           </choice>
         </attribute>
       </optional>
+      <optional>
+        <element name="distances">
+          <oneOrMore>
+            <ref name="numaDistance"/>
+          </oneOrMore>
+        </element>
+      </optional>
+    </element>
+  </define>
+
+  <define name="numaDistance">
+    <element name="sibling">
+      <attribute name="id">
+        <ref name="unsignedInt"/>
+      </attribute>
+      <attribute name="value">
+        <ref name="numaDistanceValue"/>
+      </attribute>
     </element>
   </define>
 
diff --git a/src/conf/numa_conf.c b/src/conf/numa_conf.c
index b71dc012c..5fbcc7204 100644
--- a/src/conf/numa_conf.c
+++ b/src/conf/numa_conf.c
@@ -29,6 +29,15 @@
 #include "virnuma.h"
 #include "virstring.h"
 
+/*
+ * Distance definitions defined Conform ACPI 2.0 SLIT.
+ * See include/linux/topology.h
+ */
+#define LOCAL_DISTANCE          10
+#define REMOTE_DISTANCE         20
+/* SLIT entry value is a one-byte unsigned integer. */
+#define UNREACHABLE            255
+
 #define VIR_FROM_THIS VIR_FROM_DOMAIN
 
 VIR_ENUM_IMPL(virDomainNumatuneMemMode,
@@ -48,6 +57,8 @@ VIR_ENUM_IMPL(virDomainMemoryAccess, VIR_DOMAIN_MEMORY_ACCESS_LAST,
               "shared",
               "private")
 
+typedef struct _virDomainNumaDistance virDomainNumaDistance;
+typedef virDomainNumaDistance *virDomainNumaDistancePtr;
 
 typedef struct _virDomainNumaNode virDomainNumaNode;
 typedef virDomainNumaNode *virDomainNumaNodePtr;
@@ -66,6 +77,12 @@ struct _virDomainNuma {
         virBitmapPtr nodeset;   /* host memory nodes where this guest node resides */
         virDomainNumatuneMemMode mode;  /* memory mode selection */
         virDomainMemoryAccess memAccess; /* shared memory access configuration */
+
+        struct _virDomainNumaDistance {
+            unsigned int value; /* locality value for node i->j or j->i */
+            unsigned int cellid;
+        } *distances;           /* remote node distances */
+        size_t ndistances;
     } *mem_nodes;           /* guest node configuration */
     size_t nmem_nodes;
 
@@ -686,6 +703,144 @@ virDomainNumatuneNodesetIsAvailable(virDomainNumaPtr numatune,
 }
 
 
+static int
+virDomainNumaDefNodeDistanceParseXML(virDomainNumaPtr def,
+                                     xmlXPathContextPtr ctxt,
+                                     unsigned int cur_cell)
+{
+    int ret = -1;
+    int sibling;
+    char *tmp = NULL;
+    xmlNodePtr *nodes = NULL;
+    size_t i, ndistances = def->nmem_nodes;
+
+    if (!ndistances)
+        return 0;
+
+    /* check if NUMA distances definition is present */
+    if (!virXPathNode("./distances[1]", ctxt))
+        return 0;
+
+    if ((sibling = virXPathNodeSet("./distances[1]/sibling", ctxt, &nodes)) <= 0) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("NUMA distances defined without siblings"));
+        goto cleanup;
+    }
+
+    for (i = 0; i < sibling; i++) {
+        virDomainNumaDistancePtr ldist, rdist;
+        unsigned int sibling_id, sibling_value;
+
+        /* siblings are in order of parsing or explicitly numbered */
+        if (!(tmp = virXMLPropString(nodes[i], "id"))) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Missing 'id' attribute in NUMA "
+                             "distances under 'cell id %d'"),
+                           cur_cell);
+            goto cleanup;
+        }
+
+        /* The "id" needs to be applicable */
+        if (virStrToLong_uip(tmp, NULL, 10, &sibling_id) < 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Invalid 'id' attribute in NUMA "
+                             "distances for sibling: '%s'"),
+                           tmp);
+            goto cleanup;
+        }
+        VIR_FREE(tmp);
+
+        /* The "id" needs to be within numa/cell range */
+        if (sibling_id >= ndistances) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'sibling_id %d' does not refer to a "
+                             "valid cell within NUMA 'cell id %d'"),
+                           sibling_id, cur_cell);
+            goto cleanup;
+        }
+
+        /* We need a locality value. Check and correct
+         * distance to local and distance to remote node.
+         */
+        if (!(tmp = virXMLPropString(nodes[i], "value"))) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("Missing 'value' attribute in NUMA distances "
+                             "under 'cell id %d' for 'sibling id %d'"),
+                           cur_cell, sibling_id);
+            goto cleanup;
+        }
+
+        /* The "value" needs to be applicable */
+        if (virStrToLong_uip(tmp, NULL, 10, &sibling_value) < 0) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'value %s' is invalid for "
+                             "'sibling id %d' under NUMA 'cell id %d'"),
+                           tmp, sibling_id, cur_cell);
+            goto cleanup;
+        }
+        VIR_FREE(tmp);
+
+        /* Assure LOCAL_DISTANCE <= "value" <= UNREACHABLE
+         * and correct LOCAL_DISTANCE setting if such applies.
+         */
+        if ((sibling_value < LOCAL_DISTANCE ||
+             sibling_value > UNREACHABLE) ||
+            (sibling_id == cur_cell &&
+             sibling_value != LOCAL_DISTANCE) ||
+            (sibling_id != cur_cell &&
+             sibling_value == LOCAL_DISTANCE)) {
+            virReportError(VIR_ERR_XML_ERROR,
+                           _("'value %d' is invalid for "
+                             "'sibling id %d' under NUMA 'cell id %d'"),
+                           sibling_value, sibling_id, cur_cell);
+            goto cleanup;
+        }
+
+        /* Apply the local / remote distance */
+        ldist = def->mem_nodes[cur_cell].distances;
+        if (!ldist) {
+            if (VIR_ALLOC_N(ldist, ndistances) < 0)
+                goto cleanup;
+
+            ldist[cur_cell].value = LOCAL_DISTANCE;
+            ldist[cur_cell].cellid = cur_cell;
+            def->mem_nodes[cur_cell].ndistances = ndistances;
+        }
+
+        ldist[sibling_id].cellid = sibling_id;
+        ldist[sibling_id].value = sibling_value;
+        def->mem_nodes[cur_cell].distances = ldist;
+
+        /* Apply symmetry if none given */
+        rdist = def->mem_nodes[sibling_id].distances;
+        if (!rdist) {
+            if (VIR_ALLOC_N(rdist, ndistances) < 0)
+                goto cleanup;
+
+            rdist[sibling_id].value = LOCAL_DISTANCE;
+            rdist[sibling_id].cellid = sibling_id;
+            def->mem_nodes[sibling_id].ndistances = ndistances;
+        }
+
+        rdist[cur_cell].cellid = cur_cell;
+        if (!rdist[cur_cell].value)
+            rdist[cur_cell].value = sibling_value;
+        def->mem_nodes[sibling_id].distances = rdist;
+    }
+
+    ret = 0;
+
+ cleanup:
+    if (ret) {
+        for (i = 0; i < ndistances; i++)
+            VIR_FREE(def->mem_nodes[i].distances);
+    }
+    VIR_FREE(nodes);
+    VIR_FREE(tmp);
+
+    return ret;
+}
+
 int
 virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
                             xmlXPathContextPtr ctxt)
@@ -694,7 +849,7 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
     xmlNodePtr oldNode = ctxt->node;
     char *tmp = NULL;
     int n;
-    size_t i;
+    size_t i, j;
     int ret = -1;
 
     /* check if NUMA definition is present */
@@ -712,7 +867,6 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
     def->nmem_nodes = n;
 
     for (i = 0; i < n; i++) {
-        size_t j;
         int rc;
         unsigned int cur_cell = i;
 
@@ -788,6 +942,10 @@ virDomainNumaDefCPUParseXML(virDomainNumaPtr def,
             def->mem_nodes[cur_cell].memAccess = rc;
             VIR_FREE(tmp);
         }
+
+        /* Parse NUMA distances info */
+        if (virDomainNumaDefNodeDistanceParseXML(def, ctxt, cur_cell) < 0)
+                goto cleanup;
     }
 
     ret = 0;
@@ -815,6 +973,8 @@ virDomainNumaDefCPUFormatXML(virBufferPtr buf,
     virBufferAddLit(buf, "<numa>\n");
     virBufferAdjustIndent(buf, 2);
     for (i = 0; i < ncells; i++) {
+        int ndistances;
+
         memAccess = virDomainNumaGetNodeMemoryAccessMode(def, i);
 
         if (!(cpustr = virBitmapFormat(virDomainNumaGetNodeCpumask(def, i))))
@@ -829,7 +989,32 @@ virDomainNumaDefCPUFormatXML(virBufferPtr buf,
         if (memAccess)
             virBufferAsprintf(buf, " memAccess='%s'",
                               virDomainMemoryAccessTypeToString(memAccess));
-        virBufferAddLit(buf, "/>\n");
+
+        ndistances = def->mem_nodes[i].ndistances;
+        if (!ndistances) {
+            virBufferAddLit(buf, "/>\n");
+        } else {
+            size_t j;
+            virDomainNumaDistancePtr distances = def->mem_nodes[i].distances;
+
+            virBufferAddLit(buf, ">\n");
+            virBufferAdjustIndent(buf, 2);
+            virBufferAddLit(buf, "<distances>\n");
+            virBufferAdjustIndent(buf, 2);
+            for (j = 0; j < ndistances; j++) {
+                if (distances[j].value) {
+                    virBufferAddLit(buf, "<sibling");
+                    virBufferAsprintf(buf, " id='%d'", distances[j].cellid);
+                    virBufferAsprintf(buf, " value='%d'", distances[j].value);
+                    virBufferAddLit(buf, "/>\n");
+                }
+            }
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</distances>\n");
+            virBufferAdjustIndent(buf, -2);
+            virBufferAddLit(buf, "</cell>\n");
+        }
+
         VIR_FREE(cpustr);
     }
     virBufferAdjustIndent(buf, -2);
-- 
2.13.6


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