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

[Stephan Diestelhorst <sd386@xxxxxxxxx>]

Kevin,
  I just made my own measurements on my machine (intel dual xeon 2.4 GhZ SMT 
aka. HT) results:

My machine:
SEDF: dom0 (15ms/20ms,extra on)
dom0 cpu-time after boot:  7796144577 ~  7.8 sec
idle   -"-                           40933867915 ~ 40.9 sec 
-> total boot-time: 48.7 sec
   ratio: 0.191

SEDF: dom0 (5ms/20ms,xon)
dom0 cpu-time after boot:  8300470815 ~  8.3 sec
idle   -"-                          38639540787 ~ 38.6 sec 
-> total boot-time: 46.9 sec
   ratio: 0.215
   
With BVT:
dom0 cpu-time after boot: 0x1F20E0DF4 =  8355974644 ~ 8.4 sec
idle  -"-                            0x7D5F045FA = 33654064634 ~ 33.7 sec
-> total boot-time: 42.1 sec
   ratio: 0.248
  
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

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

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

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. Did you take your samples at a similar stage during / after 
boot? I find it quite strange that they have such a massive variance!
I'll look into I/O performance during extra-time execution anyways, probably 
these artifacts will vanish when addressing this issue!

Thanks,
   Stephan


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