[libvirt] [libvirt-python][PATCH v2] examples: Introduce nodestats example

[Martin Kletzander]

On Thu, Jul 16, 2015 at 02:38:09PM +0200, Michal Privoznik wrote:
>So, this is an exercise to show libvirt capabilities. Firstly, for
>each host NUMA nodes some statistics are printed out, i.e. total
>memory and free memory. Then, for each running domain, that has memory
>strictly bound to certain host nodes, a small statistics of how much
>memory it takes is printed out too. For instance:
>
>        # ./examples/nodestats.py
>        NUMA stats
>        NUMA nodes:     0       1       2       3
>        MemTotal:       3950    3967    3937    3943
>        MemFree:        66      56      42      41
>        Domain 'fedora':
>                Overall memory: 1536 MiB nodes

Don't print "nodes" when there's no pinning.

Other than that, it works the same way in python2 and 3, it more
readable and has no errors, so ACK with the "nodes" removed when
there's no pinning for the emulator (even though it's called "overall
memory").  Also you could've closed the connection and cleanup few
things, but as this is just an example, I think that's not necessarily
needed, mainly because the code will fade the same way all of our
examples do, anyway.

>        Domain 'fedora22':
>                Overall memory: 2048 MiB nodes
>        Domain 'fedora21':
>                Overall memory: 1024 MiB nodes 0-1
>                Node 0: 1024 MiB nodes 0-1
>        Domain 'gentoo':
>                Overall memory: 4096 MiB nodes 0-3
>                Node 0: 1024 MiB nodes 0
>                Node 1: 1024 MiB nodes 1
>                Node 2: 1024 MiB nodes 2
>                Node 3: 1024 MiB nodes 3
>
>We can see 4 host NUMA nodes, all of them having roughly 4GB of RAM.
>Yeah, all of them has nearly all the memory consumed. Then, there are
>four domains running. For instance, domain 'fedora' has 1.5GB memory
>which is not pinned onto any specific host NUMA node. Domain 'gentoo' on
>the other hand has 4GB memory and has 4 NUMA nodes which are pinned 1:1
>to host nodes.
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
>
>diff to v1:
>- Martin review suggestions worked in
>- Changed the format of printing per-domain stats
>
> examples/nodestats.py | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 80 insertions(+)
> create mode 100755 examples/nodestats.py
>
>diff --git a/examples/nodestats.py b/examples/nodestats.py
>new file mode 100755
>index 0000000..4a58268
>--- /dev/null
>+++ b/examples/nodestats.py
>@@ -0,0 +1,80 @@
>+#!/usr/bin/env python
>+# Print some host NUMA node statistics
>+#
>+# Authors:
>+#   Michal Privoznik <mprivozn at redhat.com>
>+
>+import libvirt
>+import sys
>+from xml.dom import minidom
>+import libxml2
>+
>+def xpath_eval(ctxt, path):
>+    res = ctxt.xpathEval(path)
>+    if res is None or len(res) == 0:
>+        value = None
>+    else:
>+        value = res[0].content
>+    return value
>+
>+try:
>+    conn = libvirt.openReadOnly(None)
>+except libvirt.libvirtError:
>+    print("Failed to connect to the hypervisor")
>+    sys.exit(1)
>+
>+try:
>+    capsXML = conn.getCapabilities()
>+except libvirt.libvirtError:
>+    print("Failed to request capabilities")
>+    sys.exit(1)
>+
>+caps = minidom.parseString(capsXML)
>+cells = caps.getElementsByTagName("cells")[0]
>+
>+nodesIDs = [ int(proc.getAttribute("id"))
>+             for proc in cells.getElementsByTagName("cell") ]
>+
>+nodesMem = [ conn.getMemoryStats(int(proc))
>+             for proc in nodesIDs]
>+
>+doms = conn.listAllDomains(libvirt.VIR_CONNECT_LIST_DOMAINS_ACTIVE)
>+
>+domsStrict = [ proc
>+               for proc in doms
>+               if proc.numaParameters()["numa_mode"] == libvirt.VIR_DOMAIN_NUMATUNE_MEM_STRICT ]
>+
>+domsStrictCfg = {}
>+for dom in domsStrict:
>+    xmlStr = dom.XMLDesc()
>+    doc = libxml2.parseDoc(xmlStr)
>+    ctxt = doc.xpathNewContext()
>+
>+    domsStrictCfg[dom] = {}
>+
>+    pin = ctxt.xpathEval("string(/domain/numatune/memory/@nodeset)")
>+    memsize = ctxt.xpathEval("string(/domain/memory)")
>+    domsStrictCfg[dom]["memory"] = {"size": int(memsize), "pin": pin}
>+
>+    for memnode in ctxt.xpathEval("/domain/numatune/memnode"):
>+        ctxt.setContextNode(memnode)
>+        cellid = xpath_eval(ctxt, "@cellid")
>+        nodeset = xpath_eval(ctxt, "@nodeset")
>+
>+        nodesize = xpath_eval(ctxt, "/domain/cpu/numa/cell[@id='%s']/@memory" % cellid)
>+        domsStrictCfg[dom][cellid] = {"size": int(nodesize), "pin": nodeset}
>+
>+
>+print("NUMA stats")
>+print("NUMA nodes:\t" + "\t".join(str(node) for node in nodesIDs))
>+print("MemTotal:\t" + "\t".join(str(i.get("total") // 1024) for i in nodesMem))
>+print("MemFree:\t" + "\t".join(str(i.get("free") // 1024) for i in nodesMem))
>+
>+for dom, v in domsStrictCfg.items():
>+    print("Domain '%s':\t" % dom.name())
>+    print("\tOverall memory: %d MiB nodes %s" % (v["memory"]["size"] // 1024, v["memory"]["pin"]))
>+
>+    for k, node in sorted(v.items()):
>+        if k is "memory":
>+            continue
>+        print("\tNode %s:\t%d MiB nodes %s" % (k, node["size"] // 1024, node["pin"]))
>--
>2.3.6
>
>--
>libvir-list mailing list
>libvir-list at redhat.com
>https://www.redhat.com/mailman/listinfo/libvir-list
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: not available
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20150716/70078739/attachment-0001.sig>