Re: [Buildroot] [PATCH 1/1] package/busybox: speed up DHCP lease acquisition

["Yann E. MORIN" <yann.morin.1998@free.fr>]

Edgar, All,

On 2022-08-13 22:53 +0200, Edgar Bonet spake thusly:
> Commit c343e01ac4908f76520cf9a405ed87650e78dc62 made udhcpc send a
> single DHCP request (instead of 3) before going to the background, thus
> speeding up the boot process if the DHCP lease is not obtained
> immediately. Unfortunately, this can also slow down the acquisition of
> the lease as, after going to the background, udhcpc waits for 20 seconds
> (instead of 3) before retrying.
> 
> Speed up the lease acquisition by setting the retry timeout to 3
> seconds.
> 
> Signed-off-by: Edgar Bonet <bonet@grenoble.cnrs.fr>

I was unsure whether to consider this a fix or a new feature, but I
think we can really consider it a fix for a regresion, so: applied to
master, thanks.

And thanks for the detailed example!

Regards,
Yann E. MORIN.

> ---
> Hello!
> 
> While testing 2022.08-rc1 with acmesystems_acqua_a5_512mb_defconfig on a
> real Acqua board (and Ubuntu 20.04 host), I noticed that my board became
> very slow in getting a DHCP lease, which was a fast process on 2022.05.
> Wireshark showed the following DHCP traffic ("<" = received from the
> board, ">" = sent to the board):
> 
>     time (s)  packet
>     ---------------------
>     03.24 < DHCP Discover
>     06.24 > DHCP Offer
>     26.28 < DHCP Discover
>     26.28 > DHCP Offer
>     26.28 < DHCP Request
>     26.28 > DHCP ACK
> 
> Looking at the log 2022.05..2022.08-rc1, I identified the regression to
> be in commit c343e01ac4908f76520cf9a405ed87650e78dc62. This commit adds
> the option -t1 to the udhcpc command, which makes it go to the
> background after only one try, and has the unfortunate side effect of
> introducing a 20-second delay.
> 
> With this patch applied, the lease is acquired much faster:
> 
>     03.26 < DHCP Discover
>     06.26 > DHCP Offer
>     09.28 < DHCP Discover
>     09.29 > DHCP Offer
>     09.29 < DHCP Request
>     09.29 > DHCP ACK
> 
> Regards,
> 
> Edgar.
> 
>  package/busybox/busybox.config | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/busybox/busybox.config b/package/busybox/busybox.config
> index 2409cbcce1..137e44c870 100644
> --- a/package/busybox/busybox.config
> +++ b/package/busybox/busybox.config
> @@ -1022,7 +1022,7 @@ CONFIG_UDHCP_DEBUG=0
>  CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS=80
>  CONFIG_FEATURE_UDHCP_RFC3397=y
>  CONFIG_FEATURE_UDHCP_8021Q=y
> -CONFIG_IFUPDOWN_UDHCPC_CMD_OPTIONS="-t1 -b -R -O search"
> +CONFIG_IFUPDOWN_UDHCPC_CMD_OPTIONS="-t1 -A3 -b -R -O search"
>  
>  #
>  # Print Utilities
> -- 
> 2.25.1
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