[Qemu-block] Consistency of iotests 093 and 136

[Max Reitz]

Hi,

093 and 136 seem really flaky to me.  I can reproduce that by running:

$ dd if=/dev/urandom of=/dev/null

in as many shells as I have CPU cores, and then run the tests:

$ while TEST_DIR=/tmp/t0 ./check -T -raw 93; do; done

or

$ while TEST_DIR=/tmp/t0 ./check -T -raw 136; do; done

which usually fail after one or two iterations.


The exact failures vary, but for 093 it's usually something that ends with:

[...]
    self.assertTrue(check_limit(params['iops'], rd_iops + wr_iops))
AssertionError: False is not true

Or:

[...]
    self.assertTrue(check_limit(params['iops_rd'], rd_iops))
AssertionError: False is not true

etc. -- so the 10 % error range doesn't seem to be enough, I'd say.  But
will just increasing it solve the problem?


And for 136 it's usually (always?):

[...]
  File "136", line 278, in do_test_stats
    self.check_values()
  File "136", line 204, in check_values
    self.assertLess(0, stats['idle_time_ns'])
AssertionError: 0 not less than 0


Any ideas on making these more reliable?


Max

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