linux-kernel - Re: [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE

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Message-ID: <20230616122140.6e889357@kernel.org>
Date:   Fri, 16 Jun 2023 12:21:40 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Jesper Dangaard Brouer <jbrouer@...hat.com>
Cc:     Alexander Duyck <alexander.duyck@...il.com>,
        Yunsheng Lin <linyunsheng@...wei.com>, brouer@...hat.com,
        davem@...emloft.net, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        Yisen Zhuang <yisen.zhuang@...wei.com>,
        Salil Mehta <salil.mehta@...wei.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Sunil Goutham <sgoutham@...vell.com>,
        Geetha sowjanya <gakula@...vell.com>,
        Subbaraya Sundeep <sbhatta@...vell.com>,
        hariprasad <hkelam@...vell.com>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>,
        Felix Fietkau <nbd@....name>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Shayne Chen <shayne.chen@...iatek.com>,
        Sean Wang <sean.wang@...iatek.com>,
        Kalle Valo <kvalo@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Ilias Apalodimas <ilias.apalodimas@...aro.org>,
        linux-rdma@...r.kernel.org, linux-wireless@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next v4 4/5] page_pool: remove PP_FLAG_PAGE_FRAG
 flag

On Fri, 16 Jun 2023 20:59:12 +0200 Jesper Dangaard Brouer wrote:
> +       if (mem_type == MEM_TYPE_PP_NETMEM)
> +               pp_netmem_put_page(pp, page, allow_direct);
> +       else
> +               page_pool_put_full_page(pp, page, allow_direct);

Interesting, what is the netmem type? I was thinking about extending
page pool for other mem providers and what came to mind was either
optionally replacing the free / alloc with a function pointer:

https://github.com/torvalds/linux/commit/578ebda5607781c0abb26c1feae7ec8b83840768

or wrapping the PP calls with static inlines which can direct to 
a different implementation completely (like zctap / io_uring zc).

Former is better for huge pages, latter is better for IO mem
(peer-to-peer DMA). I wonder if you have different use case which
requires a different model :(