I was running some tests with the "fairtest" testcase and noticed that
successive runs could give wildly different results.
I was originally using the tip/master tree as of Sep 16, but I also
confirmed the behaviour with Linus' tree as of Sep 14 (with the
__load_balance_iterator() fix applied). The same behaviour is present
in both cases.
I'm using the test config listed at the bottom. It's pretty
straightforward.
The first run gave the following results. As expected, the system
picked a static task distribution and didn't migrate tasks during the test.
group actual(%) expected(%) avg latency(ms) max_latency(ms)
1 33.31(33.33/33.2 30.00 23/23 37/37
2 36.29 40.00 5 25
3 30.40(27.40/33.40) 30.00 22/23 60/40
On the second run, the task distribution is almost perfect, but the
system was only using one of the two cpus as seen by the difference
between actual and expected cpu time.
Warning, actual cpu time different than expected. actual: 10033.011108,
expected: 20000.000000
group actual(%) expected(%) avg latency(ms) max_latency(ms)
1 0.24(30.59/29.88) 30.00 26/27 68/58
2 39.87 40.00 20 36
3 29.89(29.87/29.91) 30.00 28/27 47/60
Any ideas what's going on?
Chris
test config file:
#delay (secs)
1
#duration (secs)
10
#groupname,share,numhogs
1,750,n
2,1000,1
3,750,n
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