Re: [Xen-devel] Credit Scheduler

[Michael xin <lizhiliwei@xxxxxxx>]

Hi~

Gaurav Somani wrote:
> 
> Hi all,
> 
> 
> I am just trying to understand the credit scheduler in xen.
> please correct me in below sequence .
> There are four VMs named V1 to V4. each having 256 credits. t is the CPU
> time.
> 
> 
>                         V1                    V2
> V3                       V4
> 
> t=0                      256                 256
> 256                    256
> t=10                    156                 256
> 256                    256
> t=20                     56                  256
> 256                    256
> t=30                    -44                  256
> 256                    256
> 
> t=40                    -44                 156
> 256                    256
> t=50                    -44                 56
> 256                    256
> t=60                     -44                -44
> 256                    256
> 
> t=70                    -44                  -44
> 156                    256
> t=80                    -44                  -44
> 56                    256
> t=90                    -44                  -44               -44
>                    256
> 
> t=100                    -44                  -44
> -44                    156
> t=110                    -44                  -44
> -44                    56
> t=120                    -44                  -44               -44
>                    -44
> 
> Credits will be reassigned when some of all credits becomes negative.
>                            IS WRONG. Scheduler will do it every 30ms
> what I understand from the BOOST state is. According to I/O event mapping
> in
> event channel, if the domain corresponding to that I/O event is in UNDER
> state than it can be upgraded to BOOST state which is highest priority
> state
> in xen.
> So currently running domain will be preempted and BOOSTED domain will
> receive the CPU.
> 
> I am having some questions
> (1) How many credits are deducted from a VM in a BOOSTed state?     the
> same as other state
> (2) If a VM has the work only for 10 ms, then what happens? Will it go to
> idle state? after 10 secs or it will consume whole 30 secs slice?          
> former is right , I think
> 
> Please provide me the direction.
> 
> Regards
> 
> Gaurav somani
> Dhirubhai Ambani Institute of ICT,
> Gandhinagar
> Gujarat, INDIA
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
> 
> 

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