[linux-lvm] It looks wrong for the timeout when lvm test running

[Heming Zhao]

Hello Zdenek,

I got your point, thank you for your explanation.


On 12/10/19 5:03 PM, Zdenek Kabelac wrote:
> Dne 10. 12. 19 v 4:23 Heming Zhao napsal(a):
>> Hello Zdenek,
>>
>> Thank you for your feedback.
>> When I switched to ramdisk backend devices, the time consuming is about 9s.
>>
>> I raised this topic for there may have a bug in timeout related codes,
>> not for why the snapshot-merge.sh costs too much time.
>>
>> The code in below overwrite silent_start when select() successfully return.
>> ```
>>             if ( select( nfds, &set, NULL, NULL, &wait ) > 0 ) {
>>                 silent_start = end; /* something happened */ <====== this line!
>>                 io.sync( false );
>>             }
>> ```
> 
> Hi
> 
> This is intentional - the idea of this 'timeout' is - that during the timeout period there is no progress on output (i.e. for 180s there was nothing printed - which likely means something got locked - there is also secondary limitation
> on number of output lines - so if something is doing endless printing loop,
> it's also catched before it fill all disk spaces on testing machine... - hopefully this explains  'something happened'  comment.
> 
> In general we don't have strict 'limit' for test length in time - although if test takes 10 minutes - it's likely not what was intended - but we don't have that rule on individual test time as speed often largely depends on machine performance.
> 
> Zdenek
>