netdev - Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for custom page providers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <5cc208d6-6116-4e9d-a48e-67290adc573a@gmail.com>
Date: Mon, 10 Jun 2024 02:12:24 +0100
From: Pavel Begunkov <asml.silence@...il.com>
To: Mina Almasry <almasrymina@...gle.com>
Cc: David Ahern <dsahern@...nel.org>, Christoph Hellwig <hch@...radead.org>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org, linux-alpha@...r.kernel.org,
 linux-mips@...r.kernel.org, linux-parisc@...r.kernel.org,
 sparclinux@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
 linux-arch@...r.kernel.org, bpf@...r.kernel.org,
 linux-kselftest@...r.kernel.org, linux-media@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, "David S. Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Donald Hunter <donald.hunter@...il.com>,
 Jonathan Corbet <corbet@....net>,
 Richard Henderson <richard.henderson@...aro.org>,
 Ivan Kokshaysky <ink@...assic.park.msu.ru>, Matt Turner
 <mattst88@...il.com>, Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
 "James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
 Helge Deller <deller@....de>, Andreas Larsson <andreas@...sler.com>,
 Jesper Dangaard Brouer <hawk@...nel.org>,
 Ilias Apalodimas <ilias.apalodimas@...aro.org>,
 Steven Rostedt <rostedt@...dmis.org>, Masami Hiramatsu
 <mhiramat@...nel.org>, Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Arnd Bergmann <arnd@...db.de>, Alexei Starovoitov <ast@...nel.org>,
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>,
 Martin KaFai Lau <martin.lau@...ux.dev>, Eduard Zingerman
 <eddyz87@...il.com>, Song Liu <song@...nel.org>,
 Yonghong Song <yonghong.song@...ux.dev>,
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>,
 Stanislav Fomichev <sdf@...gle.com>, Hao Luo <haoluo@...gle.com>,
 Jiri Olsa <jolsa@...nel.org>, Steffen Klassert
 <steffen.klassert@...unet.com>, Herbert Xu <herbert@...dor.apana.org.au>,
 Willem de Bruijn <willemdebruijn.kernel@...il.com>,
 Shuah Khan <shuah@...nel.org>, Sumit Semwal <sumit.semwal@...aro.org>,
 Christian König <christian.koenig@....com>,
 David Wei <dw@...idwei.uk>, Jason Gunthorpe <jgg@...pe.ca>,
 Yunsheng Lin <linyunsheng@...wei.com>, Shailend Chand <shailend@...gle.com>,
 Harshitha Ramamurthy <hramamurthy@...gle.com>,
 Shakeel Butt <shakeel.butt@...ux.dev>, Jeroen de Borst
 <jeroendb@...gle.com>, Praveen Kaligineedi <pkaligineedi@...gle.com>
Subject: Re: [PATCH net-next v10 02/14] net: page_pool: create hooks for
 custom page providers

On 6/7/24 17:59, Mina Almasry wrote:
> On Fri, Jun 7, 2024 at 8:47 AM Pavel Begunkov <asml.silence@...il.com> wrote:
>>
>> On 6/7/24 16:42, Pavel Begunkov wrote:
>>> On 6/7/24 15:27, David Ahern wrote:
>>>> On 6/7/24 7:42 AM, Pavel Begunkov wrote:
>>>>> I haven't seen any arguments against from the (net) maintainers so
>>>>> far. Nor I see any objection against callbacks from them (considering
>>>>> that either option adds an if).
>>>>
>>>> I have said before I do not understand why the dmabuf paradigm is not
>>>> sufficient for both device memory and host memory. A less than ideal
>>>> control path to put hostmem in a dmabuf wrapper vs extra checks and
>>>> changes in the datapath. The former should always be preferred.
>>>
>>> If we're talking about types of memory specifically, I'm not strictly
>>> against wrapping into dmabuf in kernel, but that just doesn't give
>>> anything.
>>
>> And the reason I don't have too strong of an opinion on that is
>> mainly because it's just setup/cleanup path.
>>
> 
> I agree wrapping io uring in dmabuf seems to be an unnecessary detour.
> I never understood the need or upside to do that, but it could be a
> lack of understanding on my part.
> 
> However, the concern that David brings up may materialize. I've had to
> spend a lot of time minimizing or justifying checks to the code with
> page pool benchmarks that detect even 1 cycle regressions. You may be
> asked to run the same benchmarks and minimize similar overhead.
> 
> The benchmark in question is Jesper's bench_page_pool_simple. I've
> forked it and applied it on top of net-next here:
> https://github.com/mina/linux/commit/927596f87ab5791a8a6ba8597ba2189747396e54
> 
> As io_uring ZC comes close to merging, I suspect it would be good to
> run this to understand the regression in the fast path, if any. If
> there are no to little regressions, I have no concerns over io uring
> memory not being wrapped in dmabufs, and David may agree as well.

That's the easiest part as io_uring only reusing call points
you added for devmem and thus doesn't add anything new on top
to hot paths.

-- 
Pavel Begunkov