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

[Daniel P . Berrangé]

On Fri, Jan 19, 2024 at 03:55:49PM +0000, Thomas Huth wrote:
> 
>  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)?

'g_usleep' has the same API contract, but is implemented in terms
of 'nanosleep' on *NIX. So as a quick test, try switching usleep
to g_usleep and see if we get lucky.


With regards,
Daniel
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