Re: [libvirt] [RFC PATCH 0/8 v2] Summary on block IO throttle
On 10/27/2011 11:45 PM, Eric Blake wrote:
On 10/27/2011 03:12 AM, Lei Li wrote:
> 1) Enable the blkio throttling in xml when guest is starting up.
>
> Add blkio throttling in xml as follows:
>
> <disk type='file' device='disk'>
> <driver name='qemu' type='raw'/>
> <source file='/var/lib/libvirt/images/kvm-one.img'/>
> <target dev='vda' bus='virtio'/>
> <address type='pci' domain='0x0000' bus='0x00'
slot='0x05'
> function='0x0'/>
> <iotune bps='n'.../>
> </disk>
>
> 2) Enable blkio throttling setting at guest running time.
>
> virsh blkiothrottle<domain> <device> [--bps<number>]
> [--bps_rd<number>] \
> [--bps_wr<number>] [--iops<number>] [--iops_rd<number>]
> [--iops_wr<number>]
>
> 3) The support to get the current block i/o throttling for a device -
> HMP/QMP.
>
> virsh blkiothrottle<domain> <device>
Given that the XML is named <iotune> under <disk>, we should probably
name the virsh command 'blkiotune' or 'disk-iotune', not
'blkiothrottle'.
Hi Eric, we used<iothrottle> first, I changed it since Daniel P. Berrange
proposed<iotune> for per-disk element instead of<iothrottle> when we
discussed at RFC V1.
The command 'blkiotune' already exist, supported the cgroups
blkio-controller, which handles proportional shares and throughput/iops
limits on host block devices, global to the domain, but blkio throttling
is specified per-disk and can vary across multiple disks. They are different
two mechanism.
So how about use<iothrottle> again? :)
Also, <iotune bps='n'.../> doesn't look right.
This should be similar
to the top-level XML. Here, taking into account the other proposal
for per-block-device values (which can't be tied to individual <disk>):
<domain...>
<blkiotune>
<weight>800</weight>
<device>
<path>/path/to/device</path>
<weight>200</weight>
</device>
</blkiotune>
<devices>
<disk ...>
<iotune>
<bps>800</bps>
...
</iotune>
</disk>
</devices>
</domain>
OK. I will do it at v3.
>
> daemon/remote.c | 85 +++++++++++++++++
> include/libvirt/libvirt.h.in | 25 +++++
Missing changes in docs/formatdomain.html.in (to describe the new
XML), docs/schemas/domaincommon.rng (to validate the new xml), and
tests/ (probably qemuxml2argvdata), to test it.
--
Lei