netdev - Re: [PATCH net-next] net: airoha: Add TCP LRO support

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Message-ID: <20250612155721.4bb76ab1@kernel.org>
Date: Thu, 12 Jun 2025 15:57:21 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Lorenzo Bianconi <lorenzo@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>, Andrew Lunn <andrew+netdev@...n.ch>,
 "David S. Miller" <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>,
 linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org,
 netdev@...r.kernel.org
Subject: Re: [PATCH net-next] net: airoha: Add TCP LRO support

On Thu, 12 Jun 2025 23:02:30 +0200 Lorenzo Bianconi wrote:
> > I'm not Eric but FWIW 256B is not going to help much. It's best to keep
> > the len / truesize ratio above 50%, so with 32k buffers we're talking
> > about copying multiple frames.  
> 
> what I mean here is reallocate the skb if the true size is small (e.g. below
> 256B) in order to avoid consuming the high order page from the page_pool. Maybe
> we can avoid it if reducing the page order to 2 for LRO queues provide
> comparable results.

Hm, truesize is the buffer size, right? If the driver allocated n bytes
of memory for packets it sent up the stack, the truesizes of the skbs
it generated must add up to approximately n bytes.

So if the HW places one aggregation session per buffer, and the buffer
is 32kB -- to avoid mem use ratio < 25% you'd need to copy all sessions
smaller than 8kB?

If I'm not making sense - just ignore, I haven't looked at the rest of
the driver :)