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Date: Tue, 30 May 2023 16:36:42 -0600
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Subject: Re: [PATCH net-next] net: Make gro complete function to return void
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To: Jakub Kicinski <kuba@kernel.org>, Parav Pandit <parav@nvidia.com>
Cc: Eric Dumazet <edumazet@google.com>, davem@davemloft.net,
 pabeni@redhat.com, netdev@vger.kernel.org
References: <20230529134430.492879-1-parav@nvidia.com>
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From: David Ahern <dsahern@kernel.org>
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On 5/30/23 1:39 PM, Jakub Kicinski wrote:
> On Tue, 30 May 2023 17:48:22 +0200 Eric Dumazet wrote:
>>> tcp_gro_complete seems fairly trivial. Any reason not to make it an
>>> inline and avoid another function call in the datapath?  
>>
>> Probably, although it is a regular function call, not an indirect one.
>>
>> In the grand total of driver rx napi + GRO cost, saving a few cycles
>> per GRO completed packet is quite small.
> 
> IOW please make sure you include the performance analysis quantifying
> the win, if you want to make this a static inline. Or let us know if
> the patch is good as is, I'm keeping it in pw for now.

I am not suggesting holding up this patch; just constantly looking for
these little savings here and there to keep lowering the overhead.

100G, 1500 MTU, line rate is 8.3M pps so GRO wise that would be ~180k
fewer function calls.