Re: [libvirt] [PATCH v2 1/3] conf: Add support for virtio-net.rx_queue_size

https://bugzilla.redhat.com/show_bug.cgi?id=1366989 QEMU added another virtio-net tunable [1]. It basically allows users to set the size of RX virtio ring. But because virtio-net uses two separate ring buffers to pass data from/to guest they named it explicitly rx_queue_size. We should expose it in our XML too. 1: http://lists.nongnu.org/archive/html/qemu-devel/2016-08/msg02029.html Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- docs/formatdomain.html.in | 16 ++++++++- docs/schemas/domaincommon.rng | 5 +++ src/conf/domain_conf.c | 16 +++++++++ src/conf/domain_conf.h | 1 + src/qemu/qemu_domain.c | 7 ++++ ...ml2argv-net-virtio-rxqueuesize-invalid-size.xml | 29 +++++++++++++++ .../qemuxml2argv-net-virtio-rxqueuesize.xml | 29 +++++++++++++++ tests/qemuxml2argvtest.c | 1 + .../qemuxml2xmlout-net-virtio-rxqueuesize.xml | 41 ++++++++++++++++++++++ tests/qemuxml2xmltest.c | 1 + 10 files changed, 145 insertions(+), 1 deletion(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-rxqueuesize-invalid-size.xml create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-rxqueuesize.xml create mode 100644 tests/qemuxml2xmloutdata/qemuxml2xmlout-net-virtio-rxqueuesize.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 8c15a73..be19bb9 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -4650,7 +4650,7 @@ qemu-kvm -net nic,model=? /dev/null &lt;source network='default'/&gt; &lt;target dev='vnet1'/&gt; &lt;model type='virtio'/&gt; - <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5'&gt; + <b>&lt;driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off' queues='5' rx_queue_size='256'&gt; &lt;host csum='off' gso='off' tso4='off' tso6='off' ecn='off' ufo='off' mrg_rxbuf='off'/&gt; &lt;guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/&gt; &lt;/driver&gt; @@ -4766,6 +4766,20 @@ qemu-kvm -net nic,model=? /dev/null <span class="since">virtio-net since 1.0.6 (QEMU and KVM only)</span> <span class="since">vhost-user since 1.2.17 (QEMU and KVM only)</span> </dd> + <dt><code>rx_queue_size</code></dt> + <dd> + The optional <code>rx_queue_size</code> attribute controls + the size of virtio ring for each queue as described above. + The default value is hypervisor dependent and may change + across its releases. Moreover, some hypervisors may pose + some restrictions on actual value. For instance, latest

diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 61f6dbb..05a1227 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -9517,6 +9519,17 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt, if (q > 1) def->driver.virtio.queues = q; } + if (rx_queue_size) { + unsigned int q; + if (virStrToLong_uip(rx_queue_size, NULL, 10, &q) < 0) { + virReportError(VIR_ERR_XML_DETAIL, + _("'rx_queue_size' attribute must be positive number: %s"), + rx_queue_size); + goto error; + } + if (q > 1) + def->driver.virtio.rx_queue_size = q;

+ } if ((str = virXPathString("string(./driver/host/@csum)", ctxt))) { if ((val = virTristateSwitchTypeFromString(str)) <= 0) { virReportError(VIR_ERR_CONFIG_UNSUPPORTED, @@ -9697,6 +9710,7 @@ virDomainNetDefParseXML(virDomainXMLOptionPtr xmlopt, VIR_FREE(ioeventfd); VIR_FREE(event_idx); VIR_FREE(queues); + VIR_FREE(rx_queue_size); VIR_FREE(str); VIR_FREE(filter); VIR_FREE(type); @@ -20890,6 +20904,8 @@ virDomainVirtioNetDriverFormat(char **outstr, } if (def->driver.virtio.queues) virBufferAsprintf(&buf, "queues='%u' ", def->driver.virtio.queues); + if (def->driver.virtio.rx_queue_size) + virBufferAsprintf(&buf, "rx_queue_size='%u' ", def->driver.virtio.rx_queue_size);

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c index c1fb771..29ade0e 100644 --- a/src/qemu/qemu_domain.c +++ b/src/qemu/qemu_domain.c @@ -2475,6 +2475,13 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev, "not supported by QEMU")); goto cleanup; } + + if (STREQ_NULLABLE(net->model, "virtio") && + net->driver.virtio.rx_queue_size & (net->driver.virtio.rx_queue_size - 1)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("rx_queue_size has to be a power of two")); + goto cleanup; + }