netdev - Re: [PATCH net-next] skbuff: Optimize SKB coalescing for page pool case

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Message-ID: <20230703115326.69f8953b@kernel.org>
Date: Mon, 3 Jul 2023 11:53:26 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Liang Chen <liangchen.linux@...il.com>
Cc: ilias.apalodimas@...aro.org, hawk@...nel.org, davem@...emloft.net,
 edumazet@...gle.com, pabeni@...hat.com, linyunsheng@...wei.com,
 netdev@...r.kernel.org
Subject: Re: [PATCH net-next] skbuff: Optimize SKB coalescing for page pool
 case

On Mon, 3 Jul 2023 17:12:46 +0800 Liang Chen wrote:
> As for the "pp" reference, it has the test
> page_pool_is_pp_page_frag(head_page) there. So for a non-frag pp page,
> it will be a get_page call.

You don't understand - you can't put a page from a page pool in two
skbs with pp_recycle set, unless the page is frag'ed.