netdev - Re: [PATCH net-next] selftests: net/forwarding: spawn sh inside vrf to speed up ping loop

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Message-ID: <ZsHZsemDSrG-qG__@shredder>
Date: Sun, 18 Aug 2024 14:23:29 +0300
From: Ido Schimmel <idosch@...dia.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, netdev@...r.kernel.org, edumazet@...gle.com,
	pabeni@...hat.com, shuah@...nel.org,
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH net-next] selftests: net/forwarding: spawn sh inside vrf
 to speed up ping loop

On Sat, Aug 17, 2024 at 01:36:59PM -0700, Jakub Kicinski wrote:
> Looking at timestamped output of netdev CI reveals that
> most of the time in forwarding tests for custom route
> hashing is spent on a single case, namely the test which
> uses ping (mausezahn does not support flow labels).
> 
> On a non-debug kernel we spend 714 of 730 total test
> runtime (97%) on this test case. While having flow label
> support in a traffic gen tool / mausezahn would be best,
> we can significantly speed up the loop by putting ip vrf exec
> outside of the iteration.
> 
> In a test of 1000 pings using a normal loop takes 50 seconds
> to finish. While using:
> 
>   ip vrf exec $vrf sh -c "$loop-body"
> 
> takes 12 seconds (1/4 of the time).
> 
> Some of the slowness is likely due to our inefficient virtualization
> setup, but even on my laptop running "ip link help" 16k times takes
> 25-30 seconds, so I think it's worth optimizing even for fastest
> setups.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>

Reviewed-by: Ido Schimmel <idosch@...dia.com>
Tested-by: Ido Schimmel <idosch@...dia.com>

Thanks!