[libvirt] [PATCH 1/4] domain_conf: Introduce iothreads XML

Introduce XML to allowing adding iothreads to the domain. These can be used by virtio-blk-pci devices in order to assign a specific thread to handle the workload for the device. The iothreads are the official implementation of the virtio-blk Data Plane that's been in tech preview for QEMU. Signed-off-by: John Ferlan <jferlan(a)redhat.com&gt; --- docs/formatdomain.html.in | 26 ++++++++++++++++++++++++++ docs/schemas/domaincommon.rng | 12 ++++++++++++ src/conf/domain_conf.c | 28 ++++++++++++++++++++++++++++ src/conf/domain_conf.h | 2 ++ 4 files changed, 68 insertions(+) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 59127bb..0fe10f4 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -470,6 +470,32 @@ </dd> </dl> + <h3><a name="elementsIOThreadsAllocation">IOThreads Allocation</a></h3> + <p> + IOThreads are a QEMU feature that will allow supported disk + devices to be configured to use a dedicated event loop thread + to handle block I/O requests. + <span class="since">Since 1.2.8 (QEMU only)</span> + </p> + +<pre> +&lt;domain&gt; + ... + &lt;iothreads&gt;4&lt;/iothreads&gt; + ... +&lt;/domain&gt; +</pre> + + <dl> + <dt><code>iothreads</code></dt> + <dd> + The content of this optional element defines the number + of IOThreads to be assigned to the domain for use by + virtio-blk-pci target storage devices. There should be + only 1 or 2 IOThreads per host CPU and 1 IOThread per + supported device. + </dd> + </dl> <h3><a name="elementsCPUTuning">CPU Tuning</a></h3> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 9a89dd8..b4ac483 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -632,6 +632,12 @@ </optional> <optional> + <element name="iothreads"> + <ref name="countIOThreads"/> + </element> + </optional> + + <optional> <ref name="blkiotune"/> </optional> @@ -4747,6 +4753,12 @@ <param name="minInclusive">1</param> </data> </define> + <define name="countIOThreads"> + <data type="unsignedInt"> + <param name="pattern">[0-9]+</param> + <param name="minInclusive">0</param> + </data> + </define> <define name="vcpuid"> <data type="unsignedShort"> <param name="pattern">[0-9]+</param> diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 22a7f7e..671c41c 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -11953,6 +11953,23 @@ virDomainDefParseXML(xmlDocPtr xml, } } + /* Optional - iothreads */ + n = virXPathULong("string(./iothreads[1])", ctxt, &count); + if (n == -2) { + virReportError(VIR_ERR_XML_ERROR, "%s", + _("iothreads count must be an integer")); + goto error; + } else if (n < 0) { + def->iothreads = 0; + } else { + if ((unsigned int) count != count) { + virReportError(VIR_ERR_XML_ERROR, + _("invalid iothreads count '%lu'"), count); + goto error; + } + def->iothreads = count; + } + /* Extract cpu tunables. */ if ((n = virXPathULong("string(./cputune/shares[1])", ctxt, &def->cputune.shares)) < -1) { @@ -14461,6 +14478,14 @@ virDomainDefCheckABIStability(virDomainDefPtr src, goto error; } + if (src->iothreads != dst->iothreads) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("Target domain iothreads count %u does not " + "match source %u"), + dst->iothreads, src->iothreads); + goto error; + } + if (STRNEQ(src->os.type, dst->os.type)) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, _("Target domain OS type %s does not match source %s"), @@ -17874,6 +17899,9 @@ virDomainDefFormatInternal(virDomainDefPtr def, virBufferAsprintf(buf, " current='%u'", def->vcpus); virBufferAsprintf(buf, ">%u</vcpu>\n", def->maxvcpus); + if (def->iothreads > 0) + virBufferAsprintf(buf, "<iothreads>%u</iothreads>\n", def->iothreads); + if (def->cputune.sharesSpecified || (def->cputune.nvcpupin && !virDomainIsAllVcpupinInherited(def)) || def->cputune.period || def->cputune.quota || diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h index 36ccf10..705ce32 100644 --- a/src/conf/domain_conf.h +++ b/src/conf/domain_conf.h @@ -1908,6 +1908,8 @@ struct _virDomainDef { int placement_mode; virBitmapPtr cpumask; + unsigned int iothreads; + struct { unsigned long shares; bool sharesSpecified; -- 1.9.3