[Xen-devel] [PATCH v6 for Xen 4.7 0/4] Enable per-VCPU parameter settings for RTDS scheduler

[Chong Li <lichong659@xxxxxxxxx>]

[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 4.7. 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 modify or output.

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 -v all" command. An example would be like:

# xl sched-rtds -v all
Cpupool Pool-0: sched=RTDS
Name                                ID VCPU    Period    Budget
Domain-0                             0    0     10000      4000
vm1                                  1    0       300       150
vm1                                  1    1       400       200
vm1                                  1    2     10000      4000
vm1                                  1    3      1000       500
vm2                                  2    0     10000      4000
vm2                                  2    1     10000      4000

Using "xl sched-rtds" will output the default scheduling parameters
for each domain. An example would be like:

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


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

# xl sched-rtds -d vm1 -v all
Name                                ID VCPU    Period    Budget
vm1                                  1    0       300       150
vm1                                  1    1       400       200
vm1                                  1    2     10000      4000
vm1                                  1    3      1000       500

To show a subset of the parameters of the VCPUs of a specific domain, 
please use, e.g.,"xl sched-rtds -d vm1 -v 0 -v 3" command. 
The output would be:

# xl sched-rtds -d vm1 -v 0 -v 3
Name                                ID VCPU    Period    Budget
vm1                                  1    0       300       150
vm1                                  1    3      1000       500

Using command, e.g., "xl sched-rtds -d vm1" will output the default
scheduling parameters of vm1. An example would be like:

# xl sched-rtds -d vm1
Name                                ID    Period    Budget
vm1                                  1     10000      4000


3) Users can 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 3 -p 300 -b 150".

Users can set all VCPUs with the same parameters, by one command.
e.g., "xl sched-rtds -d vm1 -v all -p 500 -b 250".


---
Previous conclusion:
On PATCH v4, our concern was about the usage of hypercall_preemption_check
and the print of warning message (both in xen). These issues are addressed 
in this patch.


CC: <dario.faggioli@xxxxxxxxxx>
CC: <george.dunlap@xxxxxxxxxxxxx>
CC: <dgolomb@xxxxxxxxxxxxxx>
CC: <mengxu@xxxxxxxxxxxxx>
CC: <jbeulich@xxxxxxxx>
CC: <wei.liu2@xxxxxxxxxx>
CC: <lichong659@xxxxxxxxx>
CC: <ian.jackson@xxxxxxxxxxxxx>
CC: <ian.campbell@xxxxxxxxxxxxx>



Chong Li (4):
  xen: enable per-VCPU parameter settings for RTDS scheduler
  libxc: enable per-VCPU parameter settings for RTDS scheduler
  libxl: enable per-VCPU parameter settings for RTDS scheduler
  xl: enable per-VCPU parameter settings for RTDS scheduler

 docs/man/xl.pod.1             |   4 +
 tools/libxc/include/xenctrl.h |  16 ++-
 tools/libxc/xc_rt.c           |  68 +++++++++
 tools/libxl/libxl.c           | 326 +++++++++++++++++++++++++++++++++++++++---
 tools/libxl/libxl.h           |  37 +++++
 tools/libxl/libxl_types.idl   |  14 ++
 tools/libxl/xl_cmdimpl.c      | 292 ++++++++++++++++++++++++++++++++-----
 tools/libxl/xl_cmdtable.c     |  10 +-
 xen/common/sched_credit.c     |   4 +
 xen/common/sched_credit2.c    |   4 +
 xen/common/sched_rt.c         | 130 +++++++++++++++--
 xen/common/schedule.c         |  15 +-
 xen/include/public/domctl.h   |  59 ++++++--
 13 files changed, 885 insertions(+), 94 deletions(-)

-- 
1.9.1


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