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Re: [libvirt] [RFC PATCH 0/8 v3] Summary on block IO throttle



On Thu, Nov 10, 2011 at 4:32 AM, Lei Li <lilei linux vnet ibm com> wrote:
> Changes since V2
>  - Implement the Python binding support for setting blkio throttling.
>  - Implement --current --live --config options support to unify the libvirt API.
>  - Add changes in docs and tests.
>  - Some changes suggested by Adam Litke, Eric Blake, Daniel P. Berrange.
>   - Change the XML schema.
>   - API name to virDomain{Set, Get}BlockIoTune.
>   - Parameters changed to make them more self-explanatory.
>   - virsh command name to blkdeviotune.
>  - And other fixups.
>
> Changes since V1
>  - Implement the support to get the block io throttling for
>   a device as read only connection - QMP/HMP.
>  - Split virDomainBlockIoThrottle into two separate functions
>     virDomainSetBlockIoThrottle - Set block I/O limits for a device
>      - Requires a connection in 'write' mode.
>      - Limits (info) structure passed as an input parameter
>     virDomainGetBlockIoThrottle - Get the current block I/O limits for a device
>      - Works on a read-only connection.
>      - Current limits are written to the output parameter (reply).
>  - And Other fixups suggested by Adam Litke, Daniel P. Berrange.
>   - For dynamically allocate the blkiothrottle struct, I will fix
>     it when implement --current --live --config options support.
>
> Today libvirt supports the cgroups blkio-controller, which handles
> proportional shares and throughput/iops limits on host block devices.
> blkio-controller does not support network file systems (NFS) or other
> QEMU remote block drivers (curl, Ceph/rbd, sheepdog) since they are
> not host block devices. QEMU I/O throttling works with all types of
> drive and can be applied independently to each drive attached to
> a guest and supports throughput/iops limits.
>
> To help add QEMU I/O throttling support to libvirt, we plan to complete
> it with add new API virDomain{Set, Get}BlockIoThrottle(), new command 'blkdeviotune'
> and Python bindings.
>
> Notes: Now all the planed features were implemented (#1#2 were implemented by
> Zhi Yong Wu), the previous comments were all fixed up too. And the qemu part patches
> have been accepted upstream just now and are expected to be part of the QEMU 1.1
> release, git tree from Zhi Yong:
>
> http://repo.or.cz/w/qemu/kevin.git/shortlog/refs/heads/block
>
>
> 1) Enable the blkio throttling in xml when guest is starting up.
>
> Add blkio throttling in xml as follows:
>
>    <disk type='file' device='disk'>
>      ...
>      <iotune>
>        <total_bytes_sec>nnn</total_bytes_sec>
>        ...
>      </iotune>
>      ...
>    </disk>
>
> 2) Enable blkio throttling setting at guest running time.
>
> virsh blkdeviotune <domain> <device> [--total_bytes_sec<number>] [--read_bytes_sec<number>] \
> [--write_bytes_sec<number>] [--total_iops_sec<number>] [--read_iops_sec<number>]
> [--write_iops_sec<number>]
>
> 3) The support to get the current block i/o throttling for a device - HMP/QMP.
>
> virsh blkiothrottle <domain> <device>
> total_bytes_sec:
> read_bytes_sec:
> write_bytes_sec:
> total_iops_sec:
> read_iops_sec:
> write_iops_sec:
>
> 4) Python binding support for setting blkio throttling.
> 5) --current --live --config options support to unify the libvirt API.
>
> virsh blkdeviotune <domain> <device> [--total_bytes_sec <number>] [--read_bytes_sec <number>]
> [--write_bytes_sec <number>] [--total_iops_sec <number>] [--read_iops_sec <number>]
> [--write_iops_sec <number>] [--config] [--live] [--current]
Thanks Li Lei for the remaining works. Below is only one reminder.
QEMU command line options have some limitations as below:

(1) global bps limit.
   -drive bps=xxx            in bytes/s
(2) only read bps limit
   -drive bps_rd=xxx         in bytes/s
(3) only write bps limit
   -drive bps_wr=xxx         in bytes/s
(4) global iops limit
   -drive iops=xxx           in ios/s
(5) only read iops limit
   -drive iops_rd=xxx        in ios/s
(6) only write iops limit
   -drive iops_wr=xxx        in ios/s
(7) the combination of some limits.
   -drive bps=xxx,iops=xxx

Known Limitations:
(1) #1 can not be used with #2, #3 together
(2) #4 can not be used with #5, #6 together

>
>
>
>  daemon/remote.c                                       |   87 +++++++
>  docs/formatdomain.html.in                             |   30 ++
>  docs/schemas/domaincommon.rng                         |   24 +
>  include/libvirt/libvirt.h.in                          |   25 ++
>  python/generator.py                                   |    2
>  python/libvirt-override-api.xml                       |   16 +
>  python/libvirt-override.c                             |   85 +++++++
>  src/conf/domain_conf.c                                |  101 ++++++++
>  src/conf/domain_conf.h                                |   12
>  src/driver.h                                          |   18 +
>  src/libvirt.c                                         |  115 +++++++++
>  src/libvirt_public.syms                               |    2
>  src/qemu/qemu_command.c                               |   33 ++
>  src/qemu/qemu_driver.c                                |  217 ++++++++++++++++++
>  src/qemu/qemu_monitor.c                               |   36 ++
>  src/qemu/qemu_monitor.h                               |   10
>  src/qemu/qemu_monitor_json.c                          |  191 +++++++++++++++
>  src/qemu/qemu_monitor_json.h                          |   10
>  src/qemu/qemu_monitor_text.c                          |  152 ++++++++++++
>  src/qemu/qemu_monitor_text.h                          |   10
>  src/remote/remote_driver.c                            |   81 ++++++
>  src/remote/remote_protocol.x                          |   39 +++
>  src/remote_protocol-structs                           |   34 ++
>  src/util/xml.h                                        |    3
>  tests/qemuxml2argvdata/qemuxml2argv-blkdeviotune.args |    4
>  tests/qemuxml2argvdata/qemuxml2argv-blkdeviotune.xml  |   36 ++
>  tests/qemuxml2argvtest.c                              |    2
>  tests/qemuxml2xmltest.c                               |    2
>  tools/virsh.c                                         |  146 ++++++++++++
>  tools/virsh.pod                                       |   23 +
>  30 files changed, 1540 insertions(+), 6 deletions(-)
>
> --
> Lei
>
> --
> libvir-list mailing list
> libvir-list redhat com
> https://www.redhat.com/mailman/listinfo/libvir-list
>



-- 
Regards,

Zhi Yong Wu


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