Re: [PATCH 09/11] iotests/264: add mirror-cancel test-case

[Eric Blake <eblake@redhat.com>]

On 11/18/20 12:04 PM, Vladimir Sementsov-Ogievskiy wrote:
> Check that cancel doesn't wait for 10s of nbd reconnect timeout.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  tests/qemu-iotests/264     | 38 ++++++++++++++++++++++++++++++--------
>  tests/qemu-iotests/264.out |  4 ++--
>  2 files changed, 32 insertions(+), 10 deletions(-)

>  
> +    def test_mirror_cancel(self):
> +        # Mirror speed limit doesn't work well enough, it seems that mirror
> +        # will run many parallel requests anyway. MAX_IN_FLIGHT is 16 and
> +        # MAX_IO_BYTES is 1M in mirror.c, so let's use 20M disk.
> +        self.init_vm(20 * 1024 * 1024)
> +        self.start_job('blockdev-mirror')

Is this comment still accurate given recent work on the mirror filter?
I'm fine taking the patch as-is and tweaking it with followups, though,
in order to make progress.

> +
> +        result = self.vm.qmp('block-job-cancel', device='drive0')
> +        self.assert_qmp(result, 'return', {})
> +
> +        start_t = time.time()
> +        self.vm.event_wait('BLOCK_JOB_CANCELLED')
> +        delta_t = time.time() - start_t
> +        self.assertTrue(delta_t < 2.0)

I hope this doesn't fail on CI platforms under heavy load.  It didn't
fail for me locally, but I hope we don't have to revisit it.  Is there
any way we can test this in a manner that is not as fragile?

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
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