netdev - Re: [PATCH net-next] selftests: drv-net: gro: increase the rcvbuf size

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Message-ID: <willemdebruijn.kernel.191adb8734bbb@gmail.com>
Date: Wed, 07 Jan 2026 18:51:38 -0500
From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
To: Jakub Kicinski <kuba@...nel.org>, 
 davem@...emloft.net
Cc: netdev@...r.kernel.org, 
 edumazet@...gle.com, 
 pabeni@...hat.com, 
 andrew+netdev@...n.ch, 
 horms@...nel.org, 
 Jakub Kicinski <kuba@...nel.org>, 
 willemb@...gle.com, 
 anubhavsinggh@...gle.com, 
 mohsin.bashr@...il.com, 
 shuah@...nel.org, 
 linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next] selftests: drv-net: gro: increase the rcvbuf
 size

Jakub Kicinski wrote:
> The gro.py test (testing software GRO) is slightly flaky when
> running against fbnic. We see one flake per roughly 20 runs in NIPA,
> mostly in ipip.large, and always including some EAGAIN:
> 
>   # Shouldn't coalesce if exceed IP max pkt size: Test succeeded
>   # Expected {65475 899 }, Total 2 packets
>   # Received {65475 899 }, Total 2 packets.
>   # Expected {64576 900 900 }, Total 3 packets
>   # Received {64576 /home/virtme/testing/wt-24/tools/testing/selftests/drivers/net/gro: could not receive: Resource temporarily unavailable
> 
> The test sends 2 large frames (64k + change). Looks like the default
> packet socket rcvbuf (~200kB) may not be large enough to hold them.
> Bump the rcvbuf to 1MB.
> 
> Add a debug print showing socket statistics to make debugging this
> issue easier in the future. Without the rcvbuf increase we see:
> 
>   # Shouldn't coalesce if exceed IP max pkt size: Test succeeded
>   # Expected {65475 899 }, Total 2 packets
>   # Received {65475 899 }, Total 2 packets.
>   # Expected {64576 900 900 }, Total 3 packets
>   # Received {64576 Socket stats: packets=7, drops=3
>                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   # /home/virtme/testing/wt-24/tools/testing/selftests/drivers/net/gro: could not receive: Resource temporarily unavailable
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

Reviewed-by: Willem de Bruijn <willemb@...gle.com>