[PATCH v1 0/4] Enabling XL to set per-VCPU parameters of a domain for RTDS scheduler

[Chong Li <lichong659@gmail.com>]

[Goal]
The current xl sched-rtds tool can only set the VCPUs of a domain to the same parameter
although the scheduler supports VCPUs with different parameters. This patchset is to
enable xl sched-rtds tool to configure the VCPUs of a domain with different parameters.

This per-VCPU settings can be used in many scenarios. For example, based on Dario's statement in our pervious discussion(http://lists.xen.org/archives/html/xen-devel/2014-09/msg00423.html), if there are two real-time applications, which have different timing requirements, running in a multi-VCPU guest domain, it is beneficial to pin these two applications to two seperate VCPUs with different scheduling parameters.

What this patchset includes is a wanted and planned feature for RTDS scheudler(http://wiki.xenproject.org/wiki/RTDS-Based-Scheduler) in Xen 4.6. The interface design of the xl sched-rtds tool is based on Meng's previous discussion with Dario, George and Wei(http://lists.xen.org/archives/html/xen-devel/2015-02/msg02606.html). Basically, there are two main changes:

1) in xl, we create an array that records all VCPUs whose parameters are about to change.

2) in libxl, we receive the array and call different xc functions to handle it.

3) in xen and libxc, we use XEN_DOMCTL_SCHEDOP_getvcpuinfo/putvcpuinfo(introduced by this patchset) as the hypercall for per-VCPU operations(get/set method).


[Usage]
With this patchset in use, xl sched-rtds tool can:

1) show the budget and period of each VCPU of each domain, by using "xl sched-rtds" command. An example would be like:

# xl sched-rtds
Cpupool Pool-0: sched=RTDS
Name                                ID VCPU    Period    Budget
Domain-0                             0    0     10000      4000
vm1                                  1    0      1000       500
vm1                                  1    1      2000      1000
vm2                                  2    0      4000      4000
vm2                                  2    1     10000      4000


2) show the budget and period of each VCPU of a specific domain, by using,       
e.g., "xl sched-rtds -d vm1" command. The output would be like:

# xl sched-rtds -d vm1
Name                                ID VCPU    Period    Budget
vm1                                  1    0      1000       500
vm1                                  1    1      2000      1000


3) set the budget and period of each VCPU of a specific domain, by using,
e.g., "xl sched-rtds -d vm1 -v 0 -p 100 -b 50" command (where "-v 0" specifies
the VCPU with ID=0). The parameters would be like:

# xl sched-rtds -d vm1
Name                                ID VCPU    Period    Budget
vm1                                  1    0       100        50
vm1                                  1    1      2000      1000


Users can also set the budget and period of multiple VCPUs of a specific domain 
with only one command, e.g., "xl sched-rtds -d vm1 -v 0 -p 100 -b 50 -v 1 -p 300 -b 150".
The parameters would be like:

# xl sched-rtds -d vm1
Name                                ID VCPU    Period    Budget
vm1                                  1    0       200       100
vm1                                  1    1       300       150

4) Users can still set the per-domain parameters (previous xl rtds tool already supported this).
e.g., "xl sched-rtds -d vm1 -p 500 -b 250". The parameters would be like:

# xl sched-rtds -d vm1
Name                                ID VCPU    Period    Budget
vm1                                  1    0       500       250
vm1                                  1    1       500       250



Chong Li (4):
  xen: enabling XL to set per-VCPU parameters of a domain for RTDS
    scheduler
  libxc: enabling XL to set per-VCPU parameters of a domain for RTDS
    scheduler
  libxl: enabling XL to set per-VCPU parameters of a domain for RTDS
    scheduler
  xl: enabling XL to set per-VCPU parameters of a domain for RTDS
    scheduler

 tools/libxc/include/xenctrl.h |   9 +++
 tools/libxc/xc_rt.c           |  52 +++++++++++++++
 tools/libxl/libxl.c           | 143 ++++++++++++++++++++++++++++++++----------
 tools/libxl/libxl.h           |   6 ++
 tools/libxl/libxl_types.idl   |  11 ++++
 tools/libxl/xl_cmdimpl.c      | 131 +++++++++++++++++++++++++++++---------
 xen/common/sched_rt.c         |  64 +++++++++++++++++++
 xen/common/schedule.c         |   4 +-
 xen/include/public/domctl.h   |  22 ++++++-
 9 files changed, 376 insertions(+), 66 deletions(-)

-- 
1.9.1