Re: [libvirt] [PATCHv2 1/3] conf: introduce 'autodeflate' attribute for memballoon device

Excessive memory balloon inflation can cause invocation of OOM-killer, when Linux is under severe memory pressure. QEMU memballoon device has a feature to release some memory at the last moment before some process will be get killed by OOM-killer. Introduced attribute allows to enable or disable this feature.

--- docs/formatdomain.html.in | 10 ++++++++++ docs/schemas/domaincommon.rng | 5 +++++ src/conf/domain_conf.c | 23 +++++++++++++++++++++++ src/conf/domain_conf.h | 1 + 4 files changed, 39 insertions(+) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index a8bd48e..7d04471 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -5954,6 +5954,16 @@ qemu-kvm -net nic,model=? /dev/null <li>'xen' &mdash; default with Xen</li> </ul> </dd> + <dt><code>autodeflate</code></dt> + <dd> + <p> + The optional <code>autodeflate</code> attribute allows to + enable/disable (values "on"/"off", respectively) the ability of the + QEMU virtio memory balloon to release some memory at the last moment + before a guest's process get killed by OOM-killer.

+ <span class="since">Since 1.3.1, QEMU and KVM only</span> + </p> + </dd> <dt><code>period</code></dt> <dd> <p> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 4804c69..512a268 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -3415,6 +3415,11 @@ <value>none</value> </choice> </attribute> + <optional> + <attribute name="autodeflate"> + <ref name="virOnOff"/> + </attribute> + </optional> <interleave> <optional> <ref name="alias"/> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 5200c27..0786d08 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -11312,6 +11312,7 @@ virDomainMemballoonDefParseXML(xmlNodePtr node, unsigned int flags) { char *model; + char *deflate; virDomainMemballoonDefPtr def; xmlNodePtr save = ctxt->node; unsigned int period = 0; @@ -11332,6 +11333,13 @@ virDomainMemballoonDefParseXML(xmlNodePtr node, goto error; } + if ((deflate = virXMLPropString(node, "autodeflate")) && + (def->autodeflate = virTristateSwitchTypeFromString(deflate)) <= 0) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("invalid autodeflate attribute value '%s'"), deflate); + goto error; + } + ctxt->node = node; if (virXPathUInt("string(./stats/@period)", ctxt, &period) < -1) { virReportError(VIR_ERR_XML_ERROR, "%s", @@ -11350,6 +11358,7 @@ virDomainMemballoonDefParseXML(xmlNodePtr node, cleanup: VIR_FREE(model); + VIR_FREE(deflate); ctxt->node = save; return def; @@ -17223,6 +17232,15 @@ virDomainMemballoonDefCheckABIStability(virDomainMemballoonDefPtr src, return false; } + if (src->autodeflate != dst->autodeflate) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("Target balloon autodeflate attribute value " + "'%s' does not match source '%s'"), + virTristateSwitchTypeToString(dst->autodeflate), + virTristateSwitchTypeToString(src->autodeflate)); + return false; + } +

if (!virDomainDeviceInfoCheckABIStability(&src->info, &dst->info)) return false; @@ -20400,6 +20418,11 @@ virDomainMemballoonDefFormat(virBufferPtr buf, } virBufferAsprintf(buf, "<memballoon model='%s'", model); + + if (def->autodeflate != VIR_TRISTATE_SWITCH_ABSENT) + virBufferAsprintf(buf, " autodeflate='%s'", + virTristateSwitchTypeToString(def->autodeflate)); + virBufferAdjustIndent(&childrenBuf, indent + 2); if (def->period) diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 952d3cc..31a0a05 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1634,6 +1634,7 @@ struct _virDomainMemballoonDef { int model; virDomainDeviceInfo info; int period; /* seconds between collections */ + int autodeflate; /* enum virTristateSwitch */ }; struct _virDomainNVRAMDef {