Re: [Xen-devel] [RFC] Add static priority into credit scheduler

[NISHIGUCHI Naoki <nisiguti@xxxxxxxxxxxxxx>]

Su, Disheng wrote:
> Not exactly, credits still makes sense for non-RT guests, but these guests only 
> propotionally share the rest of cpu(not used by RT guest) based on their 
> wieght/credit. If non-RT guest is scheduled in and out, its credit is 
> substracted as usual. It has the potential that RT guests monopolise the whole 
> cpu, if we don't have other mechanisms to prevent that.
I understand what you mean.
I doubt whether the rest of cpu not used by RT guest is reflected to 
credit of non-RT guests. If RT guest might monopolize the whole cpu, I 
think the rest of cpu is nothing, therefore non-RT guests have no credit.
> Thanks for your testing with the patch!
> In client virtualization, with static priority, the simplest way is to set the 
> primary guest and dom0 as the highest priority(can be different priority), 
> other auxiliary guests as non-RT guest. I think it *should* sovle the 
> audio/video glitch,  I don't test it though. One of issues in this way is that 
> other non-RT guests may not have enough CPU/thoughput when user is busy in 
> primary guest(e.g playing video, copying files at the same time).
>  I remembered that I heard some audio glitches in some cases with your Bcredit 
> before. Maybe static priority can be helpful but with a somewhat heavy way...
> Could you kindly have a test with this configuration?
As you sad, I set dom0 and HVM to RT priority(1) and tested.
Regretfully, HVM does not work well.

Attached file is output of "xm debug-keys r".

Best regards,
Naoki Nishiguchi

(XEN) Scheduler: SMP Credit Scheduler (credit)
(XEN) info:
(XEN)   ncpus              = 4
(XEN)   master             = 0
(XEN)   credit             = 1200
(XEN)   credit balance     = 0
(XEN)   weight             = 0
(XEN)   runq_sort          = 25322
(XEN)   default-weight     = 256
(XEN)   msecs per tick     = 10ms
(XEN)   credits per tick   = 100
(XEN)   ticks per tslice   = 3
(XEN)   ticks per acct     = 3
(XEN)   migration delay    = 0us
(XEN) idlers: 0000000a
(XEN) active vcpus:
(XEN) 
(XEN) active vcpus in rt dom:
(XEN)     1: [3.3] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     2: [3.0] pri=1 flags=0 cpu=3 credit=0 [w=256]
(XEN)     3: [3.1] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     4: [3.2] pri=1 flags=0 cpu=1 credit=300 [w=256]
(XEN)     5: [0.2] pri=1 flags=0 cpu=3 credit=0 [w=256]
(XEN)     6: [0.3] pri=1 flags=0 cpu=0 credit=-100 [w=256]
(XEN)     7: [0.0] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     8: [0.1] pri=1 flags=0 cpu=1 credit=0 [w=256]
(XEN) sched_smt_power_savings: disabled
(XEN) NOW=0x00000131829AAF25
(XEN) CPU[00]  sort=25322, sibling=00000001, core=0000000f
(XEN)   run: [0.3] pri=1 flags=0 cpu=0 credit=-100 [w=256]
(XEN)   runq:
(XEN)     1: [32767.0] pri=-64 flags=0 cpu=0
(XEN) 
(XEN) rt_runq:
(XEN) CPU[01]  sort=25322, sibling=00000002, core=0000000f
(XEN)   run: [32767.1] pri=-64 flags=0 cpu=1
(XEN)   runq:
(XEN) 
(XEN) rt_runq:
(XEN) CPU[02]  sort=25322, sibling=00000004, core=0000000f
(XEN)   run: [3.1] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)   runq:
(XEN)     1: [32767.2] pri=-64 flags=0 cpu=2
(XEN) 
(XEN) rt_runq:
(XEN)     1: [3.3] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     2: [0.0] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN) CPU[03]  sort=25322, sibling=00000008, core=0000000f
(XEN)   run: [32767.3] pri=-64 flags=0 cpu=3
(XEN)   runq:
(XEN) 
(XEN) rt_runq:
(XEN) Scheduler: SMP Credit Scheduler (credit)
(XEN) info:
(XEN)   ncpus              = 4
(XEN)   master             = 0
(XEN)   credit             = 1200
(XEN)   credit balance     = 0
(XEN)   weight             = 0
(XEN)   runq_sort          = 25322
(XEN)   default-weight     = 256
(XEN)   msecs per tick     = 10ms
(XEN)   credits per tick   = 100
(XEN)   ticks per tslice   = 3
(XEN)   ticks per acct     = 3
(XEN)   migration delay    = 0us
(XEN) idlers: 0000000a
(XEN) active vcpus:
(XEN) 
(XEN) active vcpus in rt dom:
(XEN)     1: [3.3] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     2: [3.0] pri=1 flags=0 cpu=3 credit=0 [w=256]
(XEN)     3: [3.1] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     4: [3.2] pri=1 flags=0 cpu=1 credit=300 [w=256]
(XEN)     5: [0.2] pri=1 flags=0 cpu=3 credit=0 [w=256]
(XEN)     6: [0.3] pri=1 flags=0 cpu=0 credit=-100 [w=256]
(XEN)     7: [0.0] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     8: [0.1] pri=1 flags=0 cpu=1 credit=0 [w=256]
(XEN) sched_smt_power_savings: disabled
(XEN) NOW=0x000001346A19FB21
(XEN) CPU[00]  sort=25322, sibling=00000001, core=0000000f
(XEN)   run: [0.3] pri=1 flags=0 cpu=0 credit=-100 [w=256]
(XEN)   runq:
(XEN)     1: [32767.0] pri=-64 flags=0 cpu=0
(XEN) 
(XEN) rt_runq:
(XEN) CPU[01]  sort=25322, sibling=00000002, core=0000000f
(XEN)   run: [32767.1] pri=-64 flags=0 cpu=1
(XEN)   runq:
(XEN) 
(XEN) rt_runq:
(XEN) CPU[02]  sort=25322, sibling=00000004, core=0000000f
(XEN)   run: [3.3] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)   runq:
(XEN)     1: [32767.2] pri=-64 flags=0 cpu=2
(XEN) 
(XEN) rt_runq:
(XEN)     1: [3.1] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN)     2: [0.0] pri=1 flags=0 cpu=2 credit=0 [w=256]
(XEN) CPU[03]  sort=25322, sibling=00000008, core=0000000f
(XEN)   run: [32767.3] pri=-64 flags=0 cpu=3
(XEN)   runq:
(XEN) 
(XEN) rt_runq:

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