| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] compute performace problem
I turned on rrobin
rack116-xen:~# xm dmesg | grep -i sched
(XEN) Using scheduler: Round-Robin Scheduler (rrobin)
and get the same range of execution times as with bvt:
Run Time = 183.780
Run Time = 157.980
Run Time = 65.770
Run Time = 65.530
Run Time = 86.000
Run Time = 65.530
Run Time = 79.270
Run Time = 88.150
Run Time = 69.600
Run Time = 64.900
Run Time = 246.310
Run Time = 252.230
Run Time = 64.880
" Does the domU have the same amount of memory as the native Linux? Is
Yes. I reran on native linux with 512MB and the job ran in 64s every time.
" the native Linux running on a single cpu, just like the domU?
Yes. The Dell1650 has 1 cpu installed, and no HT (PIII).
I've seen the effect on dual P4s as well.
" domU definitely quiescent apart from the mpi job?
there are some background daemons like gmond and rwhod, but that is the
same on all setups.
" directly observed the app taking 250 seconds
good question. I wondered the same thing so I now made the script
ssh to the ntp server to print the date between each run. And ...
yes the elasped times match the wallclock from the ntp server.
" If the app is cpu-bound, there are no other apps running in the domain,
" and no other domains contending for that cpu, then it is hard to
" imagine where the slowdown coudl come from.
agreed. If the native linux execution time wasn't so consistent, I'd blame
the app. I sent mail upstream to the app authors to see if they have a
suggestion. It is part of the CardioWave simulation of electical pulses
that flow through the heart (http://cardiowave.duke.edu)
I tried some tight loops and got consistent durations for time scales from
fractions of a second to 2000 seconds. The loops are like this:
time for ((i=0;i<100000;++i)); do : ;done
Here are /proc stats during the app compute phase:
xenU vmstat:
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
1 0 0 4584 456 248044 0 0 8 0 108 15 100 0 0 0
1 0 0 4584 456 248044 0 0 0 0 106 11 100 0 0 0
1 0 0 4584 456 248044 0 0 0 0 106 9 100 0 0 0
1 0 0 4584 456 248044 0 0 0 24 110 17 100 0 0 0
xen0 vmstat:
procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
r b swpd free buff cache si so bi bo in cs us sy id wa
0 0 9108 1648 2324 10532 0 0 0 24 59 28 0 0 100 0
0 0 9108 1648 2324 10532 0 0 0 0 38 14 0 0 100 0
0 0 9108 1640 2332 10532 0 0 0 88 62 37 0 1 94 5
xenU interrupt per second:
irq128: 0 Dynamic-irq misdire irq131: 0 Dynamic-irq blkif
irq129: 0 Dynamic-irq ctrl-if irq132: 7 Dynamic-irq eth0
irq130: 100 Dynamic-irq timer
xen0 interrupt per second:
irq 1: 0 Phys-irq i8042 irq128: 0 Dynamic-irq misdire
irq 6: 0 irq129: 0 Dynamic-irq ctrl-if
irq 12: 0 irq130: 38 Dynamic-irq timer
irq 14: 0 Phys-irq ide0 irq131: 0 Dynamic-irq console
irq 17: 6 Phys-irq eth0 irq132: 0 Dynamic-irq net-be-
irq 18: 6 Phys-irq aic7xxx irq133: 0 Dynamic-irq blkif-b
irq 19: 0 Phys-irq aic7xxx irq134: 0 Dynamic-irq vif2.0
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home