[Qemu-devel] qemu, numa: non-contiguous cpusets

[Borislav Petkov]

Btw,

while I got your attention, on a not-really related topic: how do we
feel about adding support for specifying a non-contiguous set of cpus
for a numa node in qemu with the -numa option? I.e., like this, for
example:

x86_64-softmmu/qemu-system-x86_64 -smp 8 -numa node,nodeid=0,cpus=0\;2\;4-5 
-numa node,nodeid=1,cpus=1\;3\;6-7

The ';' needs to be escaped from the shell but I'm open for better
suggestions.

Here's a diff:

---
diff --git a/vl.c b/vl.c
index 4e709d5c1c20..82a6c8451fb0 100644
--- a/vl.c
+++ b/vl.c
@@ -1261,9 +1261,27 @@ char *get_boot_devices_list(size_t *size)
     return list;
 }
 
+static int __numa_set_cpus(unsigned long *map, int start, int end)
+{
+    if (end >= MAX_CPUMASK_BITS) {
+        end = MAX_CPUMASK_BITS - 1;
+        fprintf(stderr,
+            "qemu: NUMA: A max of %d VCPUs are supported\n",
+             MAX_CPUMASK_BITS);
+        return -EINVAL;
+    }
+
+    if (end < start) {
+        return -EINVAL;
+    }
+
+    bitmap_set(map, start, end-start+1);
+    return 0;
+}
+
 static void numa_node_parse_cpus(int nodenr, const char *cpus)
 {
-    char *endptr;
+    char *endptr, *ptr = (char *)cpus;
     unsigned long long value, endvalue;
 
     /* Empty CPU range strings will be considered valid, they will simply
@@ -1273,7 +1291,8 @@ static void numa_node_parse_cpus(int nodenr, const char 
*cpus)
         return;
     }
 
-    if (parse_uint(cpus, &value, &endptr, 10) < 0) {
+fromthetop:
+    if (parse_uint(ptr, &value, &endptr, 10) < 0) {
         goto error;
     }
     if (*endptr == '-') {
@@ -1282,22 +1301,22 @@ static void numa_node_parse_cpus(int nodenr, const char 
*cpus)
         }
     } else if (*endptr == '\0') {
         endvalue = value;
-    } else {
-        goto error;
-    }
+    } else if (*endptr == ';') {
+       if (__numa_set_cpus(node_cpumask[nodenr], value, value) < 0) {
+               goto error;
+       }
+       endptr++;
+        if (*endptr == '\0')
+           return;
 
-    if (endvalue >= MAX_CPUMASK_BITS) {
-        endvalue = MAX_CPUMASK_BITS - 1;
-        fprintf(stderr,
-            "qemu: NUMA: A max of %d VCPUs are supported\n",
-             MAX_CPUMASK_BITS);
-    }
+       ptr = endptr;
 
-    if (endvalue < value) {
+       goto fromthetop;
+    } else {
         goto error;
     }
 
-    bitmap_set(node_cpumask[nodenr], value, endvalue-value+1);
+    __numa_set_cpus(node_cpumask[nodenr], value, endvalue);
     return;
 
 error:
--

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--