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

Zdenek Kabelac zkabelac at redhat.com
Tue Dec 10 09:03:51 UTC 2019

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 );
>             }
> ```


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 


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