[PATCH v6 4/4] qemu: support dirty ring feature
Hyman
huangy81 at chinatelecom.cn
Mon Nov 22 17:01:49 UTC 2021
在 2021/11/22 16:55, Peter Krempa 写道:
> On Sat, Nov 20, 2021 at 03:20:48 -0500, huangy81 at chinatelecom.cn wrote:
>> From: Hyman Huang(黄勇) <huangy81 at chinatelecom.cn>
>>
>> dirty ring feature was introduced in qemu-6.1, this patch add
>> corresponding feature named 'dirty-ring', which enable
>> dirty ring feature when starting vm.
>>
>> to enable the feature, libvirt add "-accel dirty-ring-size=xxx"
>> to QEMU command line, the following XML needs to be added to
>> the guest's domain description:
>>
>> <features>
>> <kvm>
>> <dirty-ring state='on' size='xxx'>
>> </kvm>
>> </features>
>>
>> if property "state=on" but property "size" not be configured, set
>> default ring size with 4096.
>>
>> since dirty ring can only be enabled by specifying "-accel" option
>> and do not support the legacy style, it seems that there's no
>> other way to work around this, so we use "-accel" option to specify
>> accelerator instead of "-machine" when building qemu commandline.
>>
>> details about the qemu "-accel" option:
>> https://lore.kernel.org/qemu-devel/3aa73987-40e8-3619-0723-9f17f73850bd@redhat.com/
>>
>> Signed-off-by: Hyman Huang(黄勇) <huangy81 at chinatelecom.cn>
>> ---
>> docs/formatdomain.rst | 18 ++++++++++--------
>> docs/schemas/domaincommon.rng | 10 ++++++++++
>> src/qemu/qemu_command.c | 6 ++++++
>> 3 files changed, 26 insertions(+), 8 deletions(-)
>>
>> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
>> index eb8c973cf1..ea69b61c70 100644
>> --- a/docs/formatdomain.rst
>> +++ b/docs/formatdomain.rst
>> @@ -1843,6 +1843,7 @@ Hypervisors may allow certain CPU / machine features to be toggled on/off.
>> <hint-dedicated state='on'/>
>> <poll-control state='on'/>
>> <pv-ipi state='off'/>
>> + <dirty-ring state='on' size='4096'/>
>> </kvm>
>> <xen>
>> <e820_host state='on'/>
>> @@ -1925,14 +1926,15 @@ are:
>> ``kvm``
>> Various features to change the behavior of the KVM hypervisor.
>>
>> - ============== ============================================================================ ======= ============================
>> - Feature Description Value Since
>> - ============== ============================================================================ ======= ============================
>> - hidden Hide the KVM hypervisor from standard MSR based discovery on, off :since:`1.2.8 (QEMU 2.1.0)`
>> - hint-dedicated Allows a guest to enable optimizations when running on dedicated vCPUs on, off :since:`5.7.0 (QEMU 2.12.0)`
>> - poll-control Decrease IO completion latency by introducing a grace period of busy waiting on, off :since:`6.10.0 (QEMU 4.2)`
>> - pv-ipi Paravirtualized send IPIs on, off :since:`7.10.0 (QEMU 3.1)`
>> - ============== ============================================================================ ======= ============================
>> + ============== ============================================================================ ====================================================== ============================
>> + Feature Description Value Since
>> + ============== ============================================================================ ====================================================== ============================
>> + hidden Hide the KVM hypervisor from standard MSR based discovery on, off :since:`1.2.8 (QEMU 2.1.0)`
>> + hint-dedicated Allows a guest to enable optimizations when running on dedicated vCPUs on, off :since:`5.7.0 (QEMU 2.12.0)`
>> + poll-control Decrease IO completion latency by introducing a grace period of busy waiting on, off :since:`6.10.0 (QEMU 4.2)`
>> + pv-ipi Paravirtualized send IPIs on, off :since:`7.10.0 (QEMU 3.1)`
>> + dirty-ring Enable dirty ring feature on, off; size - must be power of 2, range [1024,65536] :since:`7.10.0 (QEMU 6.1)`
>> + ============== ============================================================================ ====================================================== ============================
>>
>> ``xen``
>> Various features to change the behavior of the Xen hypervisor.
>
> Okay, so both hunks belong actually to the previous commit.
>
>> diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
>> index f01b7a6470..5f9fe3cc58 100644
>> --- a/docs/schemas/domaincommon.rng
>> +++ b/docs/schemas/domaincommon.rng
>> @@ -7212,6 +7212,16 @@
>> <ref name="featurestate"/>
>> </element>
>> </optional>
>> + <optional>
>> + <element name="dirty-ring">
>> + <ref name="featurestate"/>
>> + <optional>
>> + <attribute name="size">
>> + <data type="unsignedInt"/>
>> + </attribute>
>> + </optional>
>> + </element>
>> + </optional>
>> </interleave>
>> </element>
>> </define>
>
> And this one too.
>
Ok, i'll squash into the previous commit
>> diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
>> index 145596d11a..863876bfae 100644
>> --- a/src/qemu/qemu_command.c
>> +++ b/src/qemu/qemu_command.c
>> @@ -7043,6 +7043,12 @@ qemuBuildAccelCommandLineKvmOptions(virCommand *cmd,
>> g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER;
>> virCommandAddArg(cmd, "-accel");
>> virBufferAddLit(&buf, "kvm");
>> +
>> + if (def->features[VIR_DOMAIN_FEATURE_KVM] == VIR_TRISTATE_SWITCH_ON &&
>> + def->kvm_features[VIR_DOMAIN_KVM_DIRTY_RING] == VIR_TRISTATE_SWITCH_ON) {
>> + virBufferAsprintf(&buf, ",dirty-ring-size=%d", def->dirty_ring_size);
>> + }
>> +
>> virCommandAddArgBuffer(cmd, &buf);
>> }
>> }
>
> A test case is needed both for qemuxml2argvtest and qemuxml2xmltest.
>
Ok, i'll add a commit for test case implementation
More information about the libvir-list
mailing list