[Qemu-devel] [PATCH 0/2 v16] fsdev: add IO throttle support to fsdev devices

[Pradeep Jagadeesh <pradeepkiruvale@gmail.com>]

This patch set adds the IO throttling functionality to fsdev/9p devices.
So far cgroups were used for throttling IO opertions on the fsdev/9p devices.
It is difficult to use cgroups for throttling because we have to set up 
cgroups externally before we start the qemu process.
Qemu provides the throttling apis for implementing the throttling. 
Block devices already make use of these APIs for throtting the IO operations.
So, we use the same APIs to enable the throttling functionality for
fsdevices.As of now the feature is enabled only on 9p-local driver.

This feature can be used as shown in the below example:

-fsdev local,id=sdb1,path=PATH_TO_DEVICE,security_model=none,writeout=immediate,
 throttling.bps-read=4194304,throttling.bps-write=4194304  -device
 virtio-9p-pci,fsdev=sdb1,mount_tag=sdb1

The main advantages are:
 
- Easy to use because the throttling options are part of qemu cli options
- Provides a uniform way of using throttling options across block and
    fsdev/9p devices
- No need to setup cgroup to provide throttling functionality for the fsdev
  devices.
- Removes the redundant throttling code that was present in block and fsdev
  files

Missing features:

-QMP support
-Throttling support for other fsdev/9p drivers.

Thanks,
Pradeep

Pradeep Jagadeesh (2):
  fsdev: add IO throttle support to fsdev devices
  throttle: factor out duplicate code

 blockdev.c                      |  81 ++-------------------------
 fsdev/Makefile.objs             |   2 +-
 fsdev/file-op-9p.h              |   3 +
 fsdev/qemu-fsdev-opts.c         |   3 +
 fsdev/qemu-fsdev-throttle.c     | 118 ++++++++++++++++++++++++++++++++++++++++
 fsdev/qemu-fsdev-throttle.h     |  39 +++++++++++++
 hw/9pfs/9p-local.c              |   8 +++
 hw/9pfs/9p.c                    |   5 ++
 hw/9pfs/cofile.c                |   2 +
 include/qemu/throttle-options.h |  92 +++++++++++++++++++++++++++++++
 10 files changed, 275 insertions(+), 78 deletions(-)
 create mode 100644 fsdev/qemu-fsdev-throttle.c
 create mode 100644 fsdev/qemu-fsdev-throttle.h
 create mode 100644 include/qemu/throttle-options.h

-- 
1.8.3.1