[LTP] [PATCH 1/1] if-mtu-change.sh: Lower CHANGE_INTERVAL to 1

[Alexey Kodanev]

On 07.01.2021 15:02, Petr Vorel wrote:
> to make testing faster.
> 
> Tested only on netns based testing.
> 

Hi Petr,

> Signed-off-by: Petr Vorel <pvorel@suse.cz>
> ---
> Hi Alexey,
> 
> any reason why CHANGE_INTERVAL was set 5s?

It's more or less safe time for default setup. Not sure why we don't
have tst_sleep in if_updown.sh though. I think this is for preventing
link-flap errors on the switch...

For netns it's can be set far less of cause by overriding CHANGE_INTERVAL.

> It'd be nice to speedup the tests, which were slow even before
> 2d422edbf ("if-mtu-change.sh: Add max packet size detection for IPv4")
> which added 25% slowdown.
> 
> Could you please test this on two host based setup?
> 
> Kind regards,
> Petr
> 
>  testcases/network/stress/interface/if-mtu-change.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/testcases/network/stress/interface/if-mtu-change.sh b/testcases/network/stress/interface/if-mtu-change.sh
> index d2816606b..3efe00461 100755
> --- a/testcases/network/stress/interface/if-mtu-change.sh
> +++ b/testcases/network/stress/interface/if-mtu-change.sh
> @@ -11,7 +11,7 @@ TST_CLEANUP="do_cleanup"
>  . if-lib.sh
>  
>  # The interval of the mtu change [second]
> -CHANGE_INTERVAL=${CHANGE_INTERVAL:-5}
> +CHANGE_INTERVAL=${CHANGE_INTERVAL:-1}
>  
>  TST_TIMEOUT=$(((CHANGE_INTERVAL + 30) * MTU_CHANGE_TIMES))


It's better to remove TST_TIMEOUT so that CHANGE_INTERVAL can be set,
for example, to "100ms" for netns setup.