On 06/09/2017 07:58 AM, Kevin Wolf wrote: > Am 09.06.2017 um 14:14 hat Eric Blake geschrieben: >> On 06/09/2017 06:50 AM, Kevin Wolf wrote: >>> When qemu is exited, all running jobs should be cancelled successfully. >>> This adds a test for this for all types of block jobs that currently >>> exist in qemu. >>> >>> Signed-off-by: Kevin Wolf <[email protected]>
>>> +{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "SHUTDOWN", "data": {"guest": false}}
>>> +{"timestamp": {"seconds": TIMESTAMP, "microseconds": TIMESTAMP},
>>> "event": "BLOCK_JOB_CANCELLED", "data": {"device": "disk", "len": 67108864,
>>> "offset": 524288, "speed": 65536, "type": "commit"}}
>>
>> I'm worried that if you don't sanitize at least offset, you will still
>> be prone to some race conditions changing the output. You may want to
>> add in some additional filtering on the output to be safer.
>
> I considered that at first, but then I realised that these offsets are
> indeed predictable and we want to know if they change (it would likely
> mean that the throttling is broken).
>
> If you look at the individual cases, we have:
>
> * offset=512k for (intermediate) commit and streaming. This is exactly
> the buffer size for a single request and will be followed by a delay
> of eight seconds before the next chunk is copied, so we will never get
> a different value here.
>
> * offset=4M for active commit and mirror, because the mirror job has a
> larger buffer size by default, so one request completes it all. This
> number is already the maximum, so nothing is going to change here
> either.
>
> * offset=64k for backup, which works cluster by cluster. We know that
> the cluster size is exactly 64k, and while we have only one second
> of delay here, that's still plenty of time for the 'quit' command to
> arrive.
These belong in comments in the test proper, because it is not obvious
otherwise. But with comments added (so someone debugging a theoretical
test failure down the road knows what they are up against),
Reviewed-by: Eric Blake <[email protected]>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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