[Xen-devel] [PATCH v2 15/16] xl: enable for specifying node-affinity in the config file

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

in a similar way to how it is possible to specify vcpu-affinity.

Signed-off-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
---
 docs/man/xl.cfg.pod.5    |   27 ++++++++++++++--
 tools/libxl/xl_cmdimpl.c |   78 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 100 insertions(+), 5 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index 5dbc73c..733c74e 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -144,19 +144,40 @@ run on cpu #3 of the host.
 =back
 
 If this option is not specified, no vcpu to cpu pinning is established,
-and the vcpus of the guest can run on all the cpus of the host.
+and the vcpus of the guest can run on all the cpus of the host. If this
+option is specified, the intersection of the vcpu pinning mask, provided
+here, and the soft affinity mask, provided via B<cpus\_soft=> (if any),
+is utilized to compute the domain node-affinity, for driving memory
+allocations.
 
 If we are on a NUMA machine (i.e., if the host has more than one NUMA
 node) and this option is not specified, libxl automatically tries to
 place the guest on the least possible number of nodes. That, however,
 will not affect vcpu pinning, so the guest will still be able to run on
-all the cpus, it will just prefer the ones from the node it has been
-placed on. A heuristic approach is used for choosing the best node (or
+all the cpus. A heuristic approach is used for choosing the best node (or
 set of nodes), with the goals of maximizing performance for the guest
 and, at the same time, achieving efficient utilization of host cpus
 and memory. See F<docs/misc/xl-numa-placement.markdown> for more
 details.
 
+=item B<cpus_soft="CPU-LIST">
+
+Exactly as B<cpus=>, but specifies soft affinity, rather than pinning
+(also called hard affinity). Starting from Xen 4.4, and if the credit
+scheduler is used, this means the vcpus of the domain prefers to run
+these pcpus. Default is either all pcpus or xl (via libxl) guesses
+(depending on what other options are present).
+
+A C<CPU-LIST> is specified exactly as above, for B<cpus=>.
+
+If this option is not specified, the vcpus of the guest will not have
+any preference regarding on what cpu to run, and the scheduler will
+treat all the cpus where a vcpu can execute (if B<cpus=> is specified),
+or all the host cpus (if not), the same. If this option is specified,
+the intersection of the soft affinity mask, provided here, and the vcpu
+pinning, provided via B<cpus=> (if any), is utilized to compute the
+domain node-affinity, for driving memory allocations.
+
 =back
 
 =head3 CPU Scheduling
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 5a66d63..b773679 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -76,8 +76,9 @@ xlchild children[child_max];
 static const char *common_domname;
 static int fd_lock = -1;
 
-/* Stash for specific vcpu to pcpu mappping */
+/* Stash for specific vcpu to pcpu hard and soft mappping */
 static int *vcpu_to_pcpu;
+static int *vcpu_to_pcpu_soft;
 
 static const char savefileheader_magic[32]=
     "Xen saved domain, xl format\n \0 \r";
@@ -647,7 +648,8 @@ static void parse_config_data(const char *config_source,
     const char *buf;
     long l;
     XLU_Config *config;
-    XLU_ConfigList *cpus, *vbds, *nics, *pcis, *cvfbs, *cpuids, *vtpms;
+    XLU_ConfigList *cpus, *cpus_soft, *vbds, *nics, *pcis;
+    XLU_ConfigList *cvfbs, *cpuids, *vtpms;
     XLU_ConfigList *ioports, *irqs, *iomem;
     int num_ioports, num_irqs, num_iomem;
     int pci_power_mgmt = 0;
@@ -824,6 +826,50 @@ static void parse_config_data(const char *config_source,
         libxl_defbool_set(&b_info->numa_placement, false);
     }
 
+    if (!xlu_cfg_get_list (config, "cpus_soft", &cpus_soft, 0, 1)) {
+        int n_cpus = 0;
+
+        if (libxl_node_bitmap_alloc(ctx, &b_info->cpumap_soft, 0)) {
+            fprintf(stderr, "Unable to allocate cpumap_soft\n");
+            exit(1);
+        }
+
+        /* As above, use a temporary storage for the single affinities */
+        vcpu_to_pcpu_soft = xmalloc(sizeof(int) * b_info->max_vcpus);
+        memset(vcpu_to_pcpu_soft, -1, sizeof(int) * b_info->max_vcpus);
+
+        libxl_bitmap_set_none(&b_info->cpumap_soft);
+        while ((buf = xlu_cfg_get_listitem(cpus_soft, n_cpus)) != NULL) {
+            i = atoi(buf);
+            if (!libxl_bitmap_cpu_valid(&b_info->cpumap_soft, i)) {
+                fprintf(stderr, "cpu %d illegal\n", i);
+                exit(1);
+            }
+            libxl_bitmap_set(&b_info->cpumap_soft, i);
+            if (n_cpus < b_info->max_vcpus)
+                vcpu_to_pcpu_soft[n_cpus] = i;
+            n_cpus++;
+        }
+
+        /* We have a soft affinity map, disable automatic placement */
+        libxl_defbool_set(&b_info->numa_placement, false);
+    }
+    else if (!xlu_cfg_get_string (config, "cpus_soft", &buf, 0)) {
+        char *buf2 = strdup(buf);
+
+        if (libxl_node_bitmap_alloc(ctx, &b_info->cpumap_soft, 0)) {
+            fprintf(stderr, "Unable to allocate cpumap_soft\n");
+            exit(1);
+        }
+
+        libxl_bitmap_set_none(&b_info->cpumap_soft);
+        if (vcpupin_parse(buf2, &b_info->cpumap_soft))
+            exit(1);
+        free(buf2);
+
+        libxl_defbool_set(&b_info->numa_placement, false);
+    }
+
     if (!xlu_cfg_get_long (config, "memory", &l, 0)) {
         b_info->max_memkb = l * 1024;
         b_info->target_memkb = b_info->max_memkb;
@@ -2183,6 +2229,34 @@ start:
         free(vcpu_to_pcpu); vcpu_to_pcpu = NULL;
     }
 
+    /* And do the same for single vcpu to soft-affinity mapping */
+    if (vcpu_to_pcpu_soft) {
+        libxl_bitmap soft_cpumap;
+
+        ret = libxl_cpu_bitmap_alloc(ctx, &soft_cpumap, 0);
+        if (ret)
+            goto error_out;
+        for (i = 0; i < d_config.b_info.max_vcpus; i++) {
+
+            if (vcpu_to_pcpu_soft[i] != -1) {
+                libxl_bitmap_set_none(&soft_cpumap);
+                libxl_bitmap_set(&soft_cpumap, vcpu_to_pcpu_soft[i]);
+            } else {
+                libxl_bitmap_set_any(&soft_cpumap);
+            }
+            if (libxl_set_vcpuaffinity_soft(ctx, domid, i, &soft_cpumap)) {
+                fprintf(stderr, "setting soft-affinity failed "
+                        "on vcpu `%d'.\n", i);
+                libxl_bitmap_dispose(&soft_cpumap);
+                free(vcpu_to_pcpu_soft);
+                ret = ERROR_FAIL;
+                goto error_out;
+            }
+        }
+        libxl_bitmap_dispose(&soft_cpumap);
+        free(vcpu_to_pcpu_soft); vcpu_to_pcpu_soft = NULL;
+    }
+
     ret = libxl_userdata_store(ctx, domid, "xl",
                                     config_data, config_len);
     if (ret) {


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