[Xen-devel] Auto CPU rebalance ?

[Matsumoto <n_matumoto@xxxxxxxxxxxxxxxx>]

Hi,

I did a small experiment regarding Xen's 
virtual cpu mapping.
It seems sometimes manual rebalance (vcpu-pin) is required.

Is there any plan of adding auto CPU
rebalancing to the Xen scheduler? (or Xend tool?)

--  
  On a two-way server, I measured a CPU-loop benchmark with three one-way 
VMs.

 1. create VM1
  # xm vcpu-list
  Name                     ID  VCPU  CPU  State  Time(s)  CPU Affinity
  dom0                      0     0    0   -b-     139.6  any cpu
  dom0                      0     1    1   r--      99.7  any cpu
  VM1                      14     0    1   ---       0.5  any cpu

 2. create VM2
  # xm vcpu-list
  Name                     ID  VCPU  CPU  State  Time(s)  CPU Affinity
  dom0                      0     0    0   -b-     141.4  any cpu
  dom0                      0     1    1   r--     101.4  any cpu
  VM1                      14     0    1   -b-       0.9  any cpu
  VM2                      15     0    0   r--       0.5  any cpu

3. create VM3
  # xm vcpu-list
  Name                     ID  VCPU  CPU  State  Time(s)  CPU Affinity
  dom0                      0     0    0   r--     142.6  any cpu
  dom0                      0     1    1   r--     103.9  any cpu
  VM3                      16     0    1   ---       0.3  any cpu
  VM1                      14     0    1   -b-       0.9  any cpu
  VM2                      15     0    0   -b-       0.9  any cpu
 
4. shutdown VM2
  # xm shutdown VM2
  # xm list
  Name                     ID Mem(MiB) VCPUs State  Time(s)
  dom0                      0      512     2 r-----   251.9
  VM3                      16       64     1 -b----     0.8
  VM1                      14       64     1 -b----     0.9

5. benchmark CPU-loop sh on VM1 and VM3

  # xm vcpu-list
  Name                     ID  VCPU  CPU  State  Time(s)  CPU Affinity
  dom0                      0     0    0   r--     146.4  any cpu
  dom0                      0     1    1   -b-     109.2  any cpu
  VM3                      16     0    1   -b-       0.9  any cpu
  VM1                      14     0    1   -b-       1.0  any cpu
  
  # xm console VM1
  root@tiny ~ # ./test.sh
  DATE: 12/28/05
  TIME:04:11:14
  DATE: 12/28/05
  TIME:04:14:54
  root@tiny ~ #
  
  exec time is 3m40s
  
  # xm console VM3
  root@tiny ~ # ./test.sh 
  DATE: 12/28/05
  TIME:04:11:15
  DATE: 12/28/05
  TIME:04:14:55
  root@tiny ~ #
  
  exec time is 3m40s

6. manual rebalance

  # xm vcpu-pin VM1 0 0
  # xm vcpu-list
  Name                     ID  VCPU  CPU  State  Time(s)  CPU Affinity
  dom0                      0     0    0   -b-     148.5  any cpu
  dom0                      0     1    1   r--     113.4  any cpu
  VM3                      16     0    1   -b-     110.1  any cpu
  VM1                      14     0    0   -b-     110.5  0

7. same benchmark as step5, and result is 2 times better.

  # xm console VM1
  root@tiny ~ # ./test.sh
  DATE: 12/28/05
  TIME:04:19:24
  DATE: 12/28/05
  TIME:04:21:00
  root@tiny ~ #
  
  exec time is 1m36s
  
  # xm console VM3
  root@tiny ~ # ./test.sh 
  root@tiny ~ # ./test.sh 
  DATE: 12/28/05
  TIME:04:19:25
  DATE: 12/28/05
  TIME:04:20:59
  root@tiny ~ #
  
  exec time is 1m36s

Best Regards,

Matsumoto



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