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Re: [libvirt] [PATCHv2] conf: rework the cpu check for vm numa settings




On 04/22/2015 08:55 PM, Peter Krempa wrote:
On Wed, Apr 22, 2015 at 20:34:55 +0800, Luyao Huang wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1176020

We had a check for the vcpu count total number in <numa>
before, however this check is not good enough. There are
some examples:

1. one of cpu id is out of maxvcpus, can set success(cpu count = 5 < 10):

<vcpu placement='static'>10</vcpu>
<cell id='0' cpus='0-3,100' memory='512000' unit='KiB'/>

2. use the same cpu in 2 cell, can set success(cpu count = 8 < 10):
<vcpu placement='static'>10</vcpu>
<cell id='0' cpus='0-3' memory='512000' unit='KiB'/>
<cell id='1' cpus='0-3' memory='512000' unit='KiB'/>

3. use the same cpu in 2 cell, cannot set success(cpu count = 11 > 10):
<vcpu placement='static'>10</vcpu>
<cell id='0' cpus='0-6' memory='512000' unit='KiB'/>
<cell id='1' cpus='0-3' memory='512000' unit='KiB'/>

Use a new check for numa cpus, check if use a cpu exceeds maxvcpus
and if duplicate use one cpu in more than one cell.

Signed-off-by: Luyao Huang <lhuang redhat com>
---
  src/conf/domain_conf.c |  6 +-----
  src/conf/numa_conf.c   | 37 ++++++++++++++++++++++++++++++-------
  src/conf/numa_conf.h   |  2 +-
  3 files changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 479b4c2..a4a2abb 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -14234,12 +14234,8 @@ virDomainDefParseXML(xmlDocPtr xml,
      if (virDomainNumaDefCPUParseXML(def->numa, ctxt) < 0)
          goto error;
- if (virDomainNumaGetCPUCountTotal(def->numa) > def->maxvcpus) {
-        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
-                       _("Number of CPUs in <numa> exceeds the"
-                         " <vcpu> count"));
+    if (virDomainNumaCheckCPU(def->numa, def->maxvcpus) < 0)
This check could be placed after all the numa nodes are parsed and thus
would function correctly when combined with ...

Indeed


          goto error;
-    }
if (virDomainNumatuneParseXML(def->numa,
                                    def->placement_mode ==
diff --git a/src/conf/numa_conf.c b/src/conf/numa_conf.c
index 7ad3f66..2b18225 100644
--- a/src/conf/numa_conf.c
+++ b/src/conf/numa_conf.c
@@ -805,16 +805,39 @@ virDomainNumaDefCPUFormat(virBufferPtr buf,
  }
-unsigned int
-virDomainNumaGetCPUCountTotal(virDomainNumaPtr numa)
+int
+virDomainNumaCheckCPU(virDomainNumaPtr numa,
+                      unsigned short maxvcpus)
  {
-    size_t i;
-    unsigned int ret = 0;
+    size_t i,j;
- for (i = 0; i < numa->nmem_nodes; i++)
-        ret += virBitmapCountBits(virDomainNumaGetNodeCpumask(numa, i));
+    for (i = 0; i < numa->nmem_nodes; i++) {
+        virBitmapPtr nodeset = NULL;
+        ssize_t bit = -1;
+
+        nodeset = virDomainNumaGetNodeCpumask(numa, i);
+        for (j = 0; j < i; j++) {
+            if (virBitmapOverlaps(virDomainNumaGetNodeCpumask(numa, j),
+                                  nodeset)) {
... this check.

+                virReportError(VIR_ERR_INTERNAL_ERROR,
+                               _("Cannot binding one vCPU in 2 NUMA cell"
+                                 " %zu and %zu"), i, j);
This error message doesn't look very explanatory. Perhaps "NUMA cells
%zu and %zu have overlapping vCPU ids".

Good error.


+                return -1;
+            }
+        }
- return ret;
+        while ((bit = virBitmapNextSetBit(nodeset, bit)) >= 0) {
+            if (bit <= maxvcpus-1)
Incorrect spacing around the '-' operator.

right, this should be a typo mistake :)


+                continue;
This construct more-or-less reimplements virBitmapLastSetBit()

Yes, i should use virBitmapLastSetBit() in this place.


+
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("vcpu '%zu' in <numa> cell '%zu' exceeds the maxvcpus"),
+                           bit, i);
This check looks awkward. I'd go with the virDomainNumaGetCPUCountTotal
and add the check for overlapping indexes.

Hmm...okay, i think this function (virDomainNumaGetCPUCountTotal) should be renamed because this function's function will be changed after these fix.

Thanks for your quick review and help.

+            return -1;
+        }
+    }
+
+    return 0;
  }
Peter

Luyao


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