RE: [Xen-devel] Re: IDLE domain is scheduled more than dom0

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Stephan
>Diestelhorst
>Sent: Monday, July 11, 2005 11:34 PM
>
>Kevin Tian's measurements (on IA64 hardware):
>SEDF: dom0 (15/20, xoff)
>Dom0                  0x5420288a1b = 361316780571 ~ 361.3 sec
>IDLE                  0x93def9294f = 635101063503 ~ 635.1 sec
>-> total boot time: 996.4 sec ?!
>   ratio: 0.57

This data was collected until login prompt. Currently still some issue with 
timer, so that value may not be exact accurate. However I did observe that 
total boot time is about 5 times slower than BVT or the 3rd case, with IDE 
probe especially slow. I haven't figure out exact reason yet, and just wonder 
whether some different behavior on IA64 may exaggerate that issue...

>
>SEDF: dom0(15/20, xon)
>Dom0                  0x1040A91728 =  69804300072 ~  69.8 sec
>IDLE                  0x19CE88F3E7 = 110839264231 ~ 110.8 sec
>-> total boot time: 180.6 sec
>   ratio: 0.63

Sorry for this inaccurate data, upon which I stopped test at IDE probe due to 
slow progress. Rough sense is similar to first case, and anyhow the ratio is 
still not acceptable.

>
>SEDF: dom0(20/20, xoff)
>Dom0                  0x2D61AF8D5D = 194912423261 ~ 194.9 sec
>IDLE                    0x48FD92BF =   1224577727 ~   1.2 sec
>-> total boot time: 196.1 sec
>   ratio: 162.42

This one was also collected for whole boot process until login prompt.

>
>As you see, for me the fiddling with the parameters of sedf doesn't make much
>difference (even to BVT) and the idle-task always has 4-5 times as much CPU
>time as dom0. In my setup this is due to mounting of NFS devices, which takes
>quite a while, where dom0 is blocked most of the times. So our times might
>not be comparable.

So yes, they're not comparable. In your environment, too many I/O of Dom0 gives 
up time slice actively, which may shade effect when IDLE is scheduled more 
unexpectedly. However in my test environment, Dom0 never blocks actively even 
when doing I/O operation (Current status), which can be considered as a special 
case to make that corner case more obvious...

Thanks a lot,
Kevin

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