netdev - Re: [PATCH net-next v2 08/18] page_pool: make page_pool_put_page

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Message-ID: <8301d5b6-2ff6-40c0-b505-97e9eb341991@intel.com>
Date: Mon, 21 Oct 2024 16:03:30 +0200
From: Alexander Lobakin <aleksander.lobakin@...el.com>
To: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
CC: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Toke Høiland-Jørgensen
	<toke@...hat.com>, Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann
	<daniel@...earbox.net>, John Fastabend <john.fastabend@...il.com>, "Andrii
 Nakryiko" <andrii@...nel.org>, Stanislav Fomichev <sdf@...ichev.me>, "Magnus
 Karlsson" <magnus.karlsson@...el.com>,
	<nex.sw.ncis.osdt.itp.upstreaming@...el.com>, <bpf@...r.kernel.org>,
	<netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next v2 08/18] page_pool: make
 page_pool_put_page_bulk() actually handle array of pages

From: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Date: Thu, 17 Oct 2024 13:33:40 +0200

> On Tue, Oct 15, 2024 at 04:53:40PM +0200, Alexander Lobakin wrote:
>> Currently, page_pool_put_page_bulk() indeed takes an array of pointers
>> to the data, not pages, despite the name. As one side effect, when
>> you're freeing frags from &skb_shared_info, xdp_return_frame_bulk()
>> converts page pointers to virtual addresses and then
>> page_pool_put_page_bulk() converts them back.
>> Make page_pool_put_page_bulk() actually handle array of pages. Pass
>> frags directly and use virt_to_page() when freeing xdpf->data, so that
>> the PP core will then get the compound head and take care of the rest.
> 
> OTOH this one makes sense to me as a part of this patchset, plus i like
> that you are getting rid of virt to page dances.
> 
> Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@...el.com>
> 
> Any small improvements observed when doing micro benchmarks on your side?

I didn't test the perf on this one without patch 9, so dunno =\

BTW this one is needed for #9, while #9 is needed for idpf as idpf can
mix up to 3 page_pools within one frame (1 for the header, 1 for a large
frag, 1 for a small frag).

Thanks,
Olek