In some versions of qemu, both virtio-blk-pci and virtio-net-pci
devices can have an event_idx setting that determines some details of
event processing. When it is enabled, it "reduces the number of
interrupts and exits for the guest". qemu will automatically enable
this feature when it is available, but there may be cases where this
new feature could actually make performance worse (NB: no such case
has been found so far).
As a safety switch in case such a situation is encountered in the
field, this patch adds a new attribute "event_idx" to the <driver>
element of both disk and interface devices. event_idx can be set to
"on" (to force event_idx on in case qemu has it disabled by default)
or "off" (for force event_idx off). In the case that event_idx support
isn't present in qemu, the attribute is ignored (this on the advice of
the qemu developer).
docs/formatdomain.html.in: document the new flag (marking it as
"don't mess with this!"
docs/schemas/domain.rng: add event_idx in appropriate places
src/conf/domain_conf.[ch]: add event_idx to parser and formatter
src/libvirt_private.syms: export
virDomainVirtioEventIdx(From|To)String
src/qemu/qemu_capabilities.[ch]: detect and report event_idx in
disk/net
src/qemu/qemu_command.c: add event_idx parameter to qemu commandline
when appropriate.
tests/qemuxml2argvdata/qemuxml2argv-event_idx.args,
tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml,
tests/qemuxml2argvtest.c,
tests/qemuxml2xmltest.c: test cases for event_idx.
---
docs/formatdomain.html.in | 31 ++++++++++-
docs/schemas/domain.rng | 14 +++++
src/conf/domain_conf.c | 47 ++++++++++++++++-
src/conf/domain_conf.h | 11 ++++
src/libvirt_private.syms | 2 +
src/qemu/qemu_capabilities.c | 6 ++
src/qemu/qemu_capabilities.h | 2 +
src/qemu/qemu_command.c | 13 ++++-
tests/qemuxml2argvdata/qemuxml2argv-event_idx.args | 11 ++++
tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml | 57 ++++++++++++++++++++
tests/qemuxml2argvtest.c | 5 ++
tests/qemuxml2xmltest.c | 1 +
12 files changed, 196 insertions(+), 4 deletions(-)
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-event_idx.args
create mode 100644 tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 7d2ba8a..f46771d 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -904,7 +904,7 @@
</disk>
...
<disk type='network'>
- <driver name="qemu" type="raw" io="threads" ioeventfd="on"/>
+ <driver name="qemu" type="raw" io="threads" ioeventfd="on" event_idx="off"/>
<source protocol="sheepdog" name="image_name">
<host name="hostname" port="7000"/>
</source>
@@ -1004,6 +1004,19 @@
<b>In general you should leave this option alone, unless you
are very certain you know what you are doing.</b>
</li>
+ <li>
+ The optional <code>event_idx</code> attribute controls
+ some aspects of device event processing. The value can be
+ either 'on' or 'off' - if it is on, it will reduce the
+ number of interupts and exits for the guest. The default
+ is determined by QEMU; usually if the feature is
+ supported, default is on. In case there is a situation
+ where this behavior is suboptimal, this attribute provides
+ a way to force the feature off.
+ <span class="since">Since 0.9.5 (QEMU and KVM only)</span>
+ <b>In general you should leave this option alone, unless you
+ are very certain you know what you are doing.</b>
+ </li>
</ul>
</dd>
<dt><code>boot</code></dt>
@@ -1850,7 +1863,7 @@ qemu-kvm -net nic,model=? /dev/null
<source network='default'/>
<target dev='vnet1'/>
<model type='virtio'/>
- <b><driver name='vhost' txmode='iothread' ioeventfd='on'/></b>
+ <b><driver name='vhost' txmode='iothread' ioeventfd='on' event_idx='off'/></b>
</interface>
</devices>
...</pre>
@@ -1917,6 +1930,20 @@ 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>
+ <dt><code>event_idx</code></dt>
+ <dd>
+ The <code>event_idx</code> attribute controls some aspects of
+ device event processing. The value can be either 'on' or 'off'
+ - if it is on, it will reduce the number of interupts and
+ exits for the guest. The default is determined by QEMU;
+ usually if the feature is supported, default is on. In case
+ there is a situation where this behavior is suboptimal, this
+ attribute provides a way to force the feature off.
+ <span class="since">Since 0.9.5 (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>
</dl>
<h5><a name="elementsNICSTargetOverride">Overriding the target element</a></h5>
diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng
index 6ccbeed..dd8c41a 100644
--- a/docs/schemas/domain.rng
+++ b/docs/schemas/domain.rng
@@ -807,6 +807,9 @@
<optional>
<ref name="ioeventfd"/>
</optional>
+ <optional>
+ <ref name="event_idx"/>
+ </optional>
<empty/>
</element>
</define>
@@ -854,6 +857,14 @@
</choice>
</attribute>
</define>
+ <define name="event_idx">
+ <attribute name="event_idx">
+ <choice>
+ <value>on</value>
+ <value>off</value>
+ </choice>
+ </attribute>
+ </define>
<define name="controller">
<element name="controller">
<choice>
@@ -1165,6 +1176,9 @@
<optional>
<ref name="ioeventfd"/>
</optional>
+ <optional>
+ <ref name="event_idx"/>
+ </optional>
<empty/>
</element>
</optional>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 010ce57..ce1f3c5 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -182,6 +182,10 @@ VIR_ENUM_IMPL(virDomainIoEventFd, VIR_DOMAIN_IO_EVENT_FD_LAST,
"on",
"off")
+VIR_ENUM_IMPL(virDomainVirtioEventIdx, VIR_DOMAIN_VIRTIO_EVENT_IDX_LAST,
+ "default",
+ "on",
+ "off")
VIR_ENUM_IMPL(virDomainController, VIR_DOMAIN_CONTROLLER_TYPE_LAST,
"ide",
@@ -2081,6 +2085,7 @@ virDomainDiskDefParseXML(virCapsPtr caps,
char *error_policy = NULL;
char *iotag = NULL;
char *ioeventfd = NULL;
+ char *event_idx = NULL;
char *devaddr = NULL;
virStorageEncryptionPtr encryption = NULL;
char *serial = NULL;
@@ -2197,6 +2202,7 @@ virDomainDiskDefParseXML(virCapsPtr caps,
error_policy = virXMLPropString(cur, "error_policy");
iotag = virXMLPropString(cur, "io");
ioeventfd = virXMLPropString(cur, "ioeventfd");
+ event_idx = virXMLPropString(cur, "event_idx");
} else if (xmlStrEqual(cur->name, BAD_CAST "readonly")) {
def->readonly = 1;
} else if (xmlStrEqual(cur->name, BAD_CAST "shareable")) {
@@ -2351,6 +2357,24 @@ virDomainDiskDefParseXML(virCapsPtr caps,
def->ioeventfd=i;
}
+ if (event_idx) {
+ if (def->bus != VIR_DOMAIN_DISK_BUS_VIRTIO) {
+ virDomainReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("disk event_idx mode supported "
+ "only for virtio bus"));
+ goto error;
+ }
+
+ int idx;
+ if ((idx = virDomainVirtioEventIdxTypeFromString(event_idx)) <= 0) {
+ virDomainReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("unknown disk event_idx mode '%s'"),
+ event_idx);
+ goto error;
+ }
+ def->event_idx = idx;
+ }
+
if (devaddr) {
if (virDomainParseLegacyDeviceAddress(devaddr,
&def->info.addr.pci) < 0) {
@@ -2414,6 +2438,7 @@ cleanup:
VIR_FREE(error_policy);
VIR_FREE(iotag);
VIR_FREE(ioeventfd);
+ VIR_FREE(event_idx);
VIR_FREE(devaddr);
VIR_FREE(serial);
virStorageEncryptionFree(encryption);
@@ -2744,6 +2769,7 @@ virDomainNetDefParseXML(virCapsPtr caps,
char *backend = NULL;
char *txmode = NULL;
char *ioeventfd = NULL;
+ char *event_idx = NULL;
char *filter = NULL;
char *internal = NULL;
char *devaddr = NULL;
@@ -2835,6 +2861,7 @@ virDomainNetDefParseXML(virCapsPtr caps,
backend = virXMLPropString(cur, "name");
txmode = virXMLPropString(cur, "txmode");
ioeventfd = virXMLPropString(cur, "ioeventfd");
+ event_idx = virXMLPropString(cur, "event_idx");
} else if (xmlStrEqual (cur->name, BAD_CAST "filterref")) {
filter = virXMLPropString(cur, "filter");
VIR_FREE(filterparams);
@@ -3075,6 +3102,16 @@ virDomainNetDefParseXML(virCapsPtr caps,
}
def->driver.virtio.ioeventfd = i;
}
+ if (event_idx) {
+ int idx;
+ if ((idx = virDomainVirtioEventIdxTypeFromString(event_idx)) <= 0) {
+ virDomainReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+ _("unknown interface event_idx mode '%s'"),
+ event_idx);
+ goto error;
+ }
+ def->driver.virtio.event_idx = idx;
+ }
}
if (filter != NULL) {
@@ -3118,6 +3155,7 @@ cleanup:
VIR_FREE(backend);
VIR_FREE(txmode);
VIR_FREE(ioeventfd);
+ VIR_FREE(event_idx);
VIR_FREE(filter);
VIR_FREE(type);
VIR_FREE(internal);
@@ -8576,6 +8614,7 @@ virDomainDiskDefFormat(virBufferPtr buf,
const char *error_policy = virDomainDiskErrorPolicyTypeToString(def->error_policy);
const char *iomode = virDomainDiskIoTypeToString(def->iomode);
const char *ioeventfd = virDomainIoEventFdTypeToString(def->ioeventfd);
+ const char *event_idx = virDomainVirtioEventIdxTypeToString(def->event_idx);
if (!type) {
virDomainReportError(VIR_ERR_INTERNAL_ERROR,
@@ -8608,7 +8647,7 @@ virDomainDiskDefFormat(virBufferPtr buf,
type, device);
if (def->driverName || def->driverType || def->cachemode ||
- def->ioeventfd) {
+ def->ioeventfd || def->event_idx) {
virBufferAsprintf(buf, " <driver");
if (def->driverName)
virBufferAsprintf(buf, " name='%s'", def->driverName);
@@ -8622,6 +8661,8 @@ virDomainDiskDefFormat(virBufferPtr buf,
virBufferAsprintf(buf, " io='%s'", iomode);
if (def->ioeventfd)
virBufferAsprintf(buf, " ioeventfd='%s'", ioeventfd);
+ if (def->event_idx)
+ virBufferAsprintf(buf, " event_idx='%s'", event_idx);
virBufferAsprintf(buf, "/>\n");
}
@@ -8996,6 +9037,10 @@ virDomainNetDefFormat(virBufferPtr buf,
virBufferAsprintf(buf, " ioeventfd='%s'",
virDomainIoEventFdTypeToString(def->driver.virtio.ioeventfd));
}
+ if (def->driver.virtio.event_idx) {
+ virBufferAsprintf(buf, " event_idx='%s'",
+ virDomainVirtioEventIdxTypeToString(def->driver.virtio.event_idx));
+ }
virBufferAddLit(buf, "/>\n");
}
}
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 1d5af95..2cc9b06 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -209,6 +209,14 @@ enum virDomainIoEventFd {
VIR_DOMAIN_IO_EVENT_FD_LAST
};
+enum virDomainVirtioEventIdx {
+ VIR_DOMAIN_VIRTIO_EVENT_IDX_DEFAULT = 0,
+ VIR_DOMAIN_VIRTIO_EVENT_IDX_ON,
+ VIR_DOMAIN_VIRTIO_EVENT_IDX_OFF,
+
+ VIR_DOMAIN_VIRTIO_EVENT_IDX_LAST
+};
+
/* Stores the virtual disk configuration */
typedef struct _virDomainDiskDef virDomainDiskDef;
typedef virDomainDiskDef *virDomainDiskDefPtr;
@@ -229,6 +237,7 @@ struct _virDomainDiskDef {
int bootIndex;
int iomode;
int ioeventfd;
+ int event_idx;
unsigned int readonly : 1;
unsigned int shared : 1;
virDomainDeviceInfo info;
@@ -377,6 +386,7 @@ struct _virDomainNetDef {
enum virDomainNetBackendType name; /* which driver backend to use */
enum virDomainNetVirtioTxModeType txmode;
enum virDomainIoEventFd ioeventfd;
+ enum virDomainVirtioEventIdx event_idx;
} virtio;
} driver;
union {
@@ -1661,6 +1671,7 @@ VIR_ENUM_DECL(virDomainDiskErrorPolicy)
VIR_ENUM_DECL(virDomainDiskProtocol)
VIR_ENUM_DECL(virDomainDiskIo)
VIR_ENUM_DECL(virDomainIoEventFd)
+VIR_ENUM_DECL(virDomainVirtioEventIdx)
VIR_ENUM_DECL(virDomainController)
VIR_ENUM_DECL(virDomainControllerModel)
VIR_ENUM_DECL(virDomainFS)
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 64b91ee..4286fbd 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -414,6 +414,8 @@ virDomainVideoDefaultRAM;
virDomainVideoDefaultType;
virDomainVideoTypeFromString;
virDomainVideoTypeToString;
+virDomainVirtioEventIdxTypeFromString;
+virDomainVirtioEventIdxTypeToString;
virDomainVirtTypeToString;
virDomainWatchdogActionTypeFromString;
virDomainWatchdogActionTypeToString;
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 3f36212..f665de4 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -123,6 +123,8 @@ VIR_ENUM_IMPL(qemuCaps, QEMU_CAPS_LAST,
"pci-multifunction", /* 60 */
"virtio-blk-pci.ioeventfd",
"sga",
+ "virtio-blk-pci.event_idx",
+ "virtio-net-pci.event_idx",
);
struct qemu_feature_flags {
@@ -1215,6 +1217,10 @@ qemuCapsParseDeviceStr(const char *str, virBitmapPtr flags)
qemuCapsSet(flags, QEMU_CAPS_VIRTIO_IOEVENTFD);
if (strstr(str, "name \"sga\""))
qemuCapsSet(flags, QEMU_CAPS_SGA);
+ if (strstr(str, "virtio-blk-pci.event_idx"))
+ qemuCapsSet(flags, QEMU_CAPS_VIRTIO_BLK_EVENT_IDX);
+ if (strstr(str, "virtio-net-pci.event_idx"))
+ qemuCapsSet(flags, QEMU_CAPS_VIRTIO_NET_EVENT_IDX);
return 0;
}
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index d251262..13af0b9 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -98,6 +98,8 @@ enum qemuCapsFlags {
QEMU_CAPS_PCI_MULTIFUNCTION = 60, /* -device multifunction=on|off */
QEMU_CAPS_VIRTIO_IOEVENTFD = 61, /* IOeventFD feature: virtio-{net|blk}-pci.ioeventfd=on/off */
QEMU_CAPS_SGA = 62, /* Serial Graphics Adapter */
+ QEMU_CAPS_VIRTIO_BLK_EVENT_IDX = 63, /* virtio-blk-pci.event_idx */
+ QEMU_CAPS_VIRTIO_NET_EVENT_IDX = 64, /* virtio-net-pci.event_idx */
QEMU_CAPS_LAST, /* this must always be the last item */
};
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 2a48826..dbfc7d9 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1585,6 +1585,11 @@ qemuBuildDriveDevStr(virDomainDiskDefPtr disk,
case VIR_DOMAIN_DISK_BUS_VIRTIO:
virBufferAddLit(&opt, "virtio-blk-pci");
qemuBuildIoEventFdStr(&opt, disk->ioeventfd, qemuCaps);
+ if (disk->event_idx &&
+ qemuCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_BLK_EVENT_IDX)) {
+ virBufferAsprintf(&opt, ",event_idx=%s",
+ virDomainVirtioEventIdxTypeToString(disk->event_idx));
+ }
qemuBuildDeviceAddressStr(&opt, &disk->info, qemuCaps);
break;
case VIR_DOMAIN_DISK_BUS_USB:
@@ -1808,8 +1813,14 @@ qemuBuildNicDevStr(virDomainNetDefPtr net,
goto error;
}
}
- if (usingVirtio)
+ if (usingVirtio) {
qemuBuildIoEventFdStr(&buf, net->driver.virtio.ioeventfd, qemuCaps);
+ if (net->driver.virtio.event_idx &&
+ qemuCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_NET_EVENT_IDX)) {
+ virBufferAsprintf(&buf, ",event_idx=%s",
+ virDomainVirtioEventIdxTypeToString(net->driver.virtio.event_idx));
+ }
+ }
if (vlan == -1)
virBufferAsprintf(&buf, ",netdev=host%s", net->info.alias);
else
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-event_idx.args b/tests/qemuxml2argvdata/qemuxml2argv-event_idx.args
new file mode 100644
index 0000000..f6ebb60
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-event_idx.args
@@ -0,0 +1,11 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test QEMU_AUDIO_DRV=none \
+/usr/bin/qemu -S -M pc-0.13 -m 1024 -smp 1 -nodefaults \
+-monitor unix:/tmp/test-monitor,server,nowait -no-acpi \
+-boot dc -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 \
+-drive file=/var/lib/libvirt/images/f14.img,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,event_idx=on,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0 \
+-drive file=/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso,if=none,media=cdrom,id=drive-ide0-1-0 \
+-device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 \
+-device virtio-net-pci,event_idx=off,vlan=0,id=net0,mac=52:54:00:e5:48:58,bus=pci.0,addr=0x3 \
+-net user,vlan=0,name=hostnet0 -serial pty -usb -vnc 127.0.0.1:-809 -std-vga \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5
diff --git a/tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml b/tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml
new file mode 100644
index 0000000..81f2200
--- /dev/null
+++ b/tests/qemuxml2argvdata/qemuxml2argv-event_idx.xml
@@ -0,0 +1,57 @@
+<domain type='qemu'>
+ <name>test</name>
+ <uuid>bba65c0e-c049-934f-b6aa-4e2c0582acdf</uuid>
+ <memory>1048576</memory>
+ <currentMemory>1048576</currentMemory>
+ <vcpu>1</vcpu>
+ <os>
+ <type arch='x86_64' machine='pc-0.13'>hvm</type>
+ <boot dev='cdrom'/>
+ <boot dev='hd'/>
+ <bootmenu enable='yes'/>
+ </os>
+ <clock offset='utc'/>
+ <on_poweroff>destroy</on_poweroff>
+ <on_reboot>restart</on_reboot>
+ <on_crash>restart</on_crash>
+ <devices>
+ <emulator>/usr/bin/qemu</emulator>
+ <disk type='file' device='disk'>
+ <driver name='qemu' type='qcow2' event_idx='on'/>
+ <source file='/var/lib/libvirt/images/f14.img'/>
+ <target dev='vda' bus='virtio'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
+ </disk>
+ <disk type='file' device='cdrom'>
+ <driver name='qemu' type='raw'/>
+ <source file='/var/lib/libvirt/Fedora-14-x86_64-Live-KDE.iso'/>
+ <target dev='hdc' bus='ide'/>
+ <readonly/>
+ <address type='drive' controller='0' bus='1' unit='0'/>
+ </disk>
+ <controller type='virtio-serial' index='0'>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
+ </controller>
+ <controller type='ide' index='0'/>
+ <interface type='user'>
+ <mac address='52:54:00:e5:48:58'/>
+ <model type='virtio'/>
+ <driver name='vhost' event_idx='off'/>
+ </interface>
+ <serial type='pty'>
+ <target port='0'/>
+ </serial>
+ <console type='pty'>
+ <target type='serial' port='0'/>
+ </console>
+ <input type='mouse' bus='ps2'/>
+ <graphics type='vnc' port='5091' autoport='no' listen='127.0.0.1'>
+ <listen type='address' address='127.0.0.1'/>
+ </graphics>
+ <video>
+ <model type='vga' vram='9216' heads='1'/>
+ <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+ </video>
+ <memballoon model='virtio'/>
+ </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 434264a..6e8da5e 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -359,6 +359,11 @@ mymain(void)
DO_TEST("disk-ioeventfd", false,
QEMU_CAPS_DRIVE, QEMU_CAPS_VIRTIO_IOEVENTFD,
QEMU_CAPS_VIRTIO_TX_ALG, QEMU_CAPS_DEVICE);
+ DO_TEST("event_idx", false,
+ QEMU_CAPS_DRIVE,
+ QEMU_CAPS_VIRTIO_BLK_EVENT_IDX,
+ QEMU_CAPS_VIRTIO_NET_EVENT_IDX,
+ QEMU_CAPS_DEVICE);
DO_TEST("graphics-vnc", false, NONE);
DO_TEST("graphics-vnc-socket", false, NONE);
diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c
index c74f96c..4e109d5 100644
--- a/tests/qemuxml2xmltest.c
+++ b/tests/qemuxml2xmltest.c
@@ -187,6 +187,7 @@ mymain(void)
DO_TEST("smp");
DO_TEST("lease");
+ DO_TEST("event_idx");
/* These tests generate different XML */
DO_TEST_DIFFERENT("balloon-device-auto");
--
1.7.3.4
