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Re: [libvirt] [PATCHv2 4/4] nodeinfo: Get the correct CPU number on AMD Magny Cours platform



On 05/11/2012 06:41 PM, Eric Blake wrote:
From: Osier Yang<jyang redhat com>

"Instead of developing one CPU with 12 cores, the Magny Cours is
actually two 6 core “Bulldozer” CPUs combined in to one package"

I.e, each package has two NUMA nodes, and the two numa nodes share
the same core ID set (0-6), which means parsing the cores number
from sysfs doesn't work in this case.

And the wrong CPU number could cause three problems for libvirt:


[...]

@@ -265,6 +266,23 @@ int linuxNodeInfoCPUPopulate(FILE *cpuinfo,
                  &&  (*p == '\0' || *p == '.' || c_isspace(*p)))
                  nodeinfo->mhz = ui;
          }
+
+        if (STRPREFIX(buf, "cpu cores")) {
+            char *p;
+            unsigned int ui;
+            buf += 9;
+            while (*buf&&  c_isspace(*buf))
+                buf++;
+            if (*buf != ':' || !buf[1]) {
+                nodeReportError(VIR_ERR_INTERNAL_ERROR,
+                                "%s", _("parsing cpuinfo cpu MHz"));

Presumably were are parsing the total number of cpu cores ...


+                return -1;
+            }
+            if (virStrToLong_ui(buf+1,&p, 10,&ui) == 0
+                /* Accept trailing fractional part.  */

... and they don't have fractional parts.

stepping : 1
cpu MHz : 2100.073
cache size : 512 KB
physical id : 0
siblings : 12
core id : 0
cpu cores : 12
apicid : 0
initial apicid : 0

   Stefan


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