QEMU's tests/unit/test-iov times out on NetBSD and OpenBSD

[Thomas Huth <th.huth@posteo.de>]

  Hi,

since we recently introduced test timouts in QEMU's meson set up, I noticed 
that the tests/unit/test-iov times out when doing "make vm-build-netbsd 
BUILD_TARGET=check-unit" (or vm-build-openbsd).

And indeed, when increasing the timeout, you can see that the test-iov runs 
for multiple minutes on these BSDs while it finishes within few seconds on 
Linux.

I had a closer look at the test, and the problem seems to be the

  usleep(g_test_rand_int_range(0, 30));

in the test_io() function. If I get that right, the usleep() seems to be 
more or less precise on (modern) Linux, but it seems like it sleeps for 
multiple milliseconds (not microseconds) on the BSDs. Since it is used in a 
nested loop, these milliseconds add up to a long time in total during the test.

Does anybody have an idea how to fix that? Is there a more precise (but stil 
portable) way to sleep less long here? Or could we maybe remove the usleep() 
here completely (it does not seem to have a real benefit for testing as far 
as I can see)?

  Thanks,
   Thomas