[libvirt] [PATCH 4/5 v3] numatune: Support numa tuning in qemu driver.

[Osier Yang]

Implemented as setting NUMA policy between fork and exec as a hook,
using libnuma. Only support memory tuning on domain process currently.

For the nodemask out of range, will report soft warning instead of
hard error in libvirt layer. (Kernel will be silent as long as one
of set bit in the nodemask is valid on the host. E.g. For a host
has two NUMA nodes, kernel will be silent for nodemask "01010101").
So, soft warning is the only thing libvirt can do, as one might want
to specify the numa policy prior to a node that doesn't exist yet,
however, it may come as hotplug soon.
---
 src/qemu/qemu_process.c |  168 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 167 insertions(+), 1 deletions(-)

diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
index fe66100..8e09e52 100644
--- a/src/qemu/qemu_process.c
+++ b/src/qemu/qemu_process.c
@@ -39,6 +39,10 @@
 #include "qemu_hotplug.h"
 #include "qemu_bridge_filter.h"
 
+#if HAVE_NUMACTL
+# include <numa.h>
+#endif
+
 #include "datatypes.h"
 #include "logging.h"
 #include "virterror_internal.h"
@@ -1175,6 +1179,166 @@ qemuProcessDetectVcpuPIDs(struct qemud_driver *driver,
     return 0;
 }
 
+
+/*
+ * Set NUMA memory policy for qemu process, to be run between
+ * fork/exec of QEMU only.
+ */
+#if HAVE_NUMACTL
+static int
+qemuProcessInitNumaMemoryPolicy(virDomainObjPtr vm)
+{
+    struct bitmask *mask = NULL;
+    virErrorPtr orig_err = NULL;
+    virErrorPtr err = NULL;
+    int mode = -1;
+    int node = -1;
+    int ret = -1;
+    int i = 0;
+    int maxnode = 0;
+
+    VIR_DEBUG("Setting NUMA memory policy");
+
+    if (numa_available() < 0) {
+        qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                        "%s", _("Host kernel is not aware of NUMA."));
+        return -1;
+    }
+
+    if (!vm->def->numatune.memory.nodemask)
+        return 0;
+
+    if (VIR_ALLOC(mask) < 0) {
+        virReportOOMError();
+        return -1;
+    }
+
+    mask->size = VIR_DOMAIN_CPUMASK_LEN / sizeof (unsigned long);
+    if (VIR_ALLOC_N(mask->maskp, mask->size) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
+    /* Convert nodemask to NUMA bitmask. */
+    for (i = 0; i < VIR_DOMAIN_CPUMASK_LEN; i++) {
+        int cur = 0;
+        int mod = 0;
+
+        if (i) {
+            cur = i / (8 * sizeof (unsigned long));
+            mod = i % (8 * sizeof (unsigned long));
+        }
+
+        if (vm->def->numatune.memory.nodemask[i]) {
+           mask->maskp[cur] |= 1 << mod;
+        }
+    }
+
+    maxnode = numa_max_node() + 1;
+
+    for (i = 0; i < mask->size; i++) {
+        if (i < (maxnode % (8 * sizeof (unsigned long)))) {
+            if (mask->maskp[i] & ~maxnode) {
+                VIR_WARN("nodeset is out of range, there is only %d NUMA "
+                         "nodes on host", maxnode);
+                break;
+             }
+
+             continue;
+        }
+
+        if (mask->maskp[i]) {
+            VIR_WARN("nodeset is out of range, there is only %d NUMA nodes "
+                      "on host", maxnode);
+        }
+    }
+
+    orig_err = virSaveLastError();
+    mode = vm->def->numatune.memory.mode;
+
+    if (mode == VIR_DOMAIN_NUMATUNE_MEM_STRICT) {
+        numa_set_bind_policy(1);
+        numa_set_membind(mask);
+        numa_set_bind_policy(0);
+
+        err = virGetLastError();
+        if ((err && (err->code != orig_err->code)) ||
+            (err && !orig_err)) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("Failed to bind memory to specified nodeset: %s"),
+                            err ? err->message : _("unknown error"));
+            virResetLastError();
+            goto cleanup;
+        }
+    } else if (mode == VIR_DOMAIN_NUMATUNE_MEM_PREFERRED) {
+        int nnodes = 0;
+        for (i = 0; i < mask->size; i++) {
+            if (numa_bitmask_isbitset(mask, i)) {
+                node = i;
+                nnodes++;
+            }
+        }
+
+        if (nnodes != 1) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            "%s", _("NUMA memory tuning in 'preferred' mode "
+                                    "only supports single node"));
+            goto cleanup;
+        }
+
+        numa_set_bind_policy(0);
+        numa_set_preferred(node);
+
+        err = virGetLastError();
+        if ((err && (err->code != orig_err->code)) ||
+            (err && !orig_err)) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("Failed to set memory policy as preferred to specified "
+                              "node: %s"), err ? err->message : _("unknown error"));
+            virResetLastError();
+            goto cleanup;
+        }
+    } else if (mode == VIR_DOMAIN_NUMATUNE_MEM_INTERLEAVE) {
+        numa_set_interleave_mask(mask);
+
+        err = virGetLastError();
+        if ((err && (err->code != orig_err->code)) ||
+            (err && !orig_err)) {
+            qemuReportError(VIR_ERR_INTERNAL_ERROR,
+                            _("Failed to interleave memory to specified nodeset: %s"),
+                            err ? err->message : _("unknown error"));
+            virResetLastError();
+            goto cleanup;
+        }
+    } else {
+        /* XXX: Shouldn't go here, as we already do checking when
+         * parsing domain XML.
+         */
+        qemuReportError(VIR_ERR_XML_ERROR,
+                        "%s", _("Invalid mode for memory NUMA tuning."));
+        goto cleanup;
+    }
+
+    ret = 0;
+
+cleanup:
+    numa_bitmask_free(mask);
+    return ret;
+}
+#else
+static int
+qemuProcessInitNumaMemoryPolicy(virDomainObjPtr vm)
+{
+    if (vm->def->numatune.memory.nodemask) {
+        qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("libvirt is compiled without NUMA tuning support"));
+
+        return -1;
+    }
+
+    return 0;
+}
+#endif
+
 /*
  * To be run between fork/exec of QEMU only
  */
@@ -1891,6 +2055,9 @@ static int qemuProcessHook(void *data)
     if (qemuProcessInitCpuAffinity(h->vm) < 0)
         goto cleanup;
 
+    if (qemuProcessInitNumaMemoryPolicy(h->vm) < 0)
+        return -1;
+
     VIR_DEBUG("Setting up security labeling");
     if (virSecurityManagerSetProcessLabel(h->driver->securityManager, h->vm) < 0)
         goto cleanup;
@@ -1902,7 +2069,6 @@ cleanup:
     return ret;
 }
 
-
 int
 qemuProcessPrepareMonitorChr(struct qemud_driver *driver,
                              virDomainChrSourceDefPtr monConfig,
-- 
1.7.4