[libvirt] [RFC PATCH 0/8 v2] Summary on block IO throttle

[Daniel P. Berrange]

On Fri, Oct 28, 2011 at 04:59:40PM +0800, Lei Li wrote:
> 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.

This is a per-device tunable, so just insert 'dev' into the command
name. ie:

   blkdeviotune

Daniel
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