Re: [libvirt] [PATCH 3/3] qemu: add busy polling support

From: Sahid Orentino Ferdjaoui <sahid.ferdjaoui(a)redhat.com&gt; This patch finalizes support of 'poll_us' attribute as an option of the NIC driver-specific element, the commit also takes care of hotplug. <devices> <interface type='ethernet'> <mac address='52:54:00:23:bc:ba'/> <model type='virtio'/> <driver name="vhost" poll_us='50'/> </interface> </devices> That option is supported for all networks which are using a tap device. To be used the backend should be specificly set to use vhost.

Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui(a)redhat.com&gt; --- docs/formatdomain.html.in | 12 ++++++++++- docs/schemas/domaincommon.rng | 5 +++++ src/qemu/qemu_command.c | 22 +++++++++++++++++++++ src/qemu/qemu_hotplug.c | 12 +++++++++++ .../qemuxml2argv-net-virtio-netdev-pollus-fail.xml | 23 ++++++++++++++++++++++ ...xml2argv-net-virtio-netdev-pollus-qemu-fail.xml | 23 ++++++++++++++++++++++ .../qemuxml2argv-net-virtio-netdev-pollus.args | 23 ++++++++++++++++++++++ .../qemuxml2argv-net-virtio-netdev-pollus.xml | 23 ++++++++++++++++++++++ tests/qemuxml2argvtest.c | 9 +++++++++

9 files changed, 151 insertions(+), 1 deletion(-) create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-fail.xml create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-qemu-fail.xml create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.args create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.xml diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 52119f0..7bfeabc 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -5043,7 +5043,7 @@ qemu-kvm -net nic,model=? /dev/null &lt;model type='virtio'/&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;guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off' poll_us='50'/&gt; &lt;/driver&gt; </b> &lt;/interface&gt; @@ -5171,6 +5171,16 @@ qemu-kvm -net nic,model=? /dev/null <b>In general you should leave this option alone, unless you are very certain you know what you are doing.</b> </dd> + <dd> + The optional <code>poll_us</code> attribute configure the + maximum number of microseconds that could be spent on busy + polling. It improves the performance, but requires more + CPU. This option is only available with vhost backend driver. + <span class="since">Since 2.7.0 (QEMU and KVM only)</span><br/><br/> + + <b>In general you should leave this option alone, unless you + are very certain you know what you are doing.</b> + </dd> <dt>virtio options</dt> <dd> For virtio interfaces, diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index 4950ddc..f304385 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -2687,6 +2687,11 @@ <optional> <ref name="event_idx"/> </optional> + <optional> + <attribute name='poll_us'> + <ref name='positiveInteger'/> + </attribute> + </optional> </group> </choice> <ref name="virtioOptions"/>

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 8c12b2b..412496e 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -3955,6 +3955,9 @@ qemuBuildHostNetStr(virDomainNetDefPtr net, } if (net->tune.sndbuf_specified) virBufferAsprintf(&buf, "sndbuf=%lu,", net->tune.sndbuf); + if (net->driver.virtio.pollus) + virBufferAsprintf(&buf, "poll-us=%u,", + net->driver.virtio.pollus); } virObjectUnref(cfg); @@ -8451,6 +8454,25 @@ qemuBuildInterfaceCommandLine(virQEMUDriverPtr driver, return -1; } + if (net->driver.virtio.pollus > 0) { + if (net->driver.virtio.name != VIR_DOMAIN_NET_BACKEND_TYPE_VHOST) {

+ virReportError( + VIR_ERR_CONFIG_UNSUPPORTED, + _("Busy polling is only supported with vhost backend driver"));

+ return -1; + } + /* Nothing besides TAP devices supports busy polling. */ + if (!(actualType == VIR_DOMAIN_NET_TYPE_NETWORK || + actualType == VIR_DOMAIN_NET_TYPE_BRIDGE || + actualType == VIR_DOMAIN_NET_TYPE_DIRECT || + actualType == VIR_DOMAIN_NET_TYPE_ETHERNET)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("Busy polling is not supported for: %s"), + virDomainNetTypeToString(actualType)); + return -1; + } + } + /* and only TAP devices support nwfilter rules */ if (net->filter && !(actualType == VIR_DOMAIN_NET_TYPE_NETWORK || diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c index 0b8d3d8..33884b7 100644 --- a/src/qemu/qemu_hotplug.c +++ b/src/qemu/qemu_hotplug.c @@ -995,6 +995,18 @@ qemuDomainAttachNetDevice(virQEMUDriverPtr driver, return -1; } + /* and nothing besides TAP devices supports busy polling. */ + if (net->driver.virtio.pollus > 0 && + !(actualType == VIR_DOMAIN_NET_TYPE_NETWORK || + actualType == VIR_DOMAIN_NET_TYPE_BRIDGE || + actualType == VIR_DOMAIN_NET_TYPE_DIRECT || + actualType == VIR_DOMAIN_NET_TYPE_ETHERNET)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, + _("Busy polling is not supported for: %s"), + virDomainNetTypeToString(actualType)); + return -1; + }

+ /* and only TAP devices support nwfilter rules */ if (net->filter && !(actualType == VIR_DOMAIN_NET_TYPE_NETWORK || diff --git a/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-fail.xml b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-fail.xml new file mode 100644 index 0000000..3b664b9 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-fail.xml @@ -0,0 +1,23 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219100</memory> + <currentMemory unit='KiB'>219100</currentMemory> + <vcpu placement='static'>1</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu-system-i686</emulator> + <interface type='ethernet'> + <mac address='52:54:00:23:bc:ba'/> + <model type='virtio'/> + <driver poll_us='50'/>

+ </interface> + </devices> +</domain> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-qemu-fail.xml b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-qemu-fail.xml new file mode 100644 index 0000000..18999c3 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus-qemu-fail.xml @@ -0,0 +1,23 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219100</memory> + <currentMemory unit='KiB'>219100</currentMemory> + <vcpu placement='static'>1</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu-system-i686</emulator> + <interface type='ethernet'> + <mac address='52:54:00:23:bc:ba'/> + <model type='virtio'/> + <driver name="qemu" poll_us='50'/>

+ </interface> + </devices> +</domain> diff --git a/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.args b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.args new file mode 100644 index 0000000..8d44134 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.args @@ -0,0 +1,23 @@ +LC_ALL=C \ +PATH=/bin \ +HOME=/home/test \ +USER=test \ +LOGNAME=test \ +QEMU_AUDIO_DRV=none \ +/usr/bin/qemu-system-i686 \ +-name QEMUGuest1 \ +-S \ +-M pc \ +-m 214 \ +-smp 1,sockets=1,cores=1,threads=1 \ +-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \ +-nographic \ +-nodefaults \ +-monitor unix:/tmp/lib/domain--1-QEMUGuest1/monitor.sock,server,nowait \ +-no-acpi \ +-boot c \ +-usb \ +-netdev tap,fd=3,id=hostnet0,poll-us=50 \ +-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:23:bc:ba,bus=pci.0,\ +addr=0x3 \ +-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 diff --git a/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.xml b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.xml new file mode 100644 index 0000000..46ef7d6 --- /dev/null +++ b/tests/qemuxml2argvdata/qemuxml2argv-net-virtio-netdev-pollus.xml @@ -0,0 +1,23 @@ +<domain type='qemu'> + <name>QEMUGuest1</name> + <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid> + <memory unit='KiB'>219100</memory> + <currentMemory unit='KiB'>219100</currentMemory> + <vcpu placement='static'>1</vcpu> + <os> + <type arch='i686' machine='pc'>hvm</type> + <boot dev='hd'/> + </os> + <clock offset='utc'/> + <on_poweroff>destroy</on_poweroff> + <on_reboot>restart</on_reboot> + <on_crash>destroy</on_crash> + <devices> + <emulator>/usr/bin/qemu-system-i686</emulator> + <interface type='ethernet'> + <mac address='52:54:00:23:bc:ba'/> + <model type='virtio'/> + <driver name="vhost" poll_us='50'/> + </interface> + </devices> +</domain> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 799aea9..54d1b07 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -1133,6 +1133,15 @@ mymain(void) QEMU_CAPS_NODEFCONFIG); DO_TEST("net-virtio-netdev", QEMU_CAPS_NETDEV, QEMU_CAPS_NODEFCONFIG); + DO_TEST("net-virtio-netdev-pollus", + QEMU_CAPS_NETDEV, + QEMU_CAPS_VHOST_NET_POLL_US); + DO_TEST_FAILURE("net-virtio-netdev-pollus-fail", + QEMU_CAPS_NETDEV, + QEMU_CAPS_VHOST_NET_POLL_US); + DO_TEST_FAILURE("net-virtio-netdev-pollus-qemu-fail", + QEMU_CAPS_NETDEV, + QEMU_CAPS_VHOST_NET_POLL_US); DO_TEST("net-virtio-s390", QEMU_CAPS_VIRTIO_S390); DO_TEST("net-virtio-ccw",