[Qemu-devel] [PATCH v6 0/4] The intro of QEMU block I/O throttling

[Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>]

The main goal of the patch is to effectively cap the disk I/O speed or counts of one single VM.It is only one draft, so it unavoidably has some drawbacks, if you catch them, please let me know.

The patch will mainly introduce one block I/O throttling algorithm, one timer and one block queue for each I/O limits enabled drive.

When a block request is coming in, the throttling algorithm will check if its I/O rate or counts exceed the limits; if yes, then it will enqueue to the block queue; The timer will handle the I/O requests in it.

Some available features follow 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 coexist with #2, #3
(2) #4 can not coexist with #5, #6
(3) When bps/iops limits are specified to a small value such as 511 bytes/s, this VM will hang up. We are considering how to handle this senario.

Changes since code V5:
  Mainly fix the aio callback issue for block queue.
  Adjust codes based on Ram Pai's comments.

Zhi Yong Wu (4):
  block: add the command line support
  block: add the block queue support
  block: add block timer and block throttling algorithm
  qmp/hmp: add block_set_io_throttle

 v5: add qmp/hmp support. 
     Adjust the codes based on stefan's comments
     qmp/hmp: add block_set_io_throttle
 
 v4: fix memory leaking based on ryan's feedback.
 
 v3: Added the code for extending slice time, and modified the method to compute wait time for the timer.
 
 v2: The codes V2 for QEMU disk I/O limits.
     Modified the codes mainly based on stefan's comments.
 
 v1: Submit the codes for QEMU disk I/O limits.
     Only a code draft.

 Makefile.objs     |    2 +-
 block.c           |  324 +++++++++++++++++++++++++++++++++++++++++++++++++++--
 block.h           |    6 +-
 block/blk-queue.c |  226 +++++++++++++++++++++++++++++++++++++
 block/blk-queue.h |   63 ++++++++++
 block_int.h       |   30 +++++
 blockdev.c        |   98 ++++++++++++++++
 blockdev.h        |    2 +
 hmp-commands.hx   |   15 +++
 qemu-config.c     |   24 ++++
 qemu-options.hx   |    1 +
 qerror.c          |    4 +
 qerror.h          |    3 +
 qmp-commands.hx   |   52 +++++++++-
 14 files changed, 837 insertions(+), 13 deletions(-)
 create mode 100644 block/blk-queue.c
 create mode 100644 block/blk-queue.h

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1.7.6