[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <779b9542-4170-483a-af54-ca0dd471f774@kernel.org>
Date: Wed, 1 May 2024 15:58:59 +0200
From: Jesper Dangaard Brouer <hawk@...nel.org>
To: Jens Axboe <axboe@...nel.dk>, Mina Almasry <almasrymina@...gle.com>
Cc: David Wei <dw@...idwei.uk>, 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>,
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>,
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>,
David Ahern <dsahern@...nel.org>,
Willem de Bruijn <willemdebruijn.kernel@...il.com>,
Shuah Khan <shuah@...nel.org>, Sumit Semwal <sumit.semwal@...aro.org>,
Christian König <christian.koenig@....com>,
Amritha Nambiar <amritha.nambiar@...el.com>,
Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
Alexander Mikhalitsyn <alexander@...alicyn.com>,
Kaiyuan Zhang <kaiyuanz@...gle.com>, Christian Brauner <brauner@...nel.org>,
Simon Horman <horms@...nel.org>, David Howells <dhowells@...hat.com>,
Florian Westphal <fw@...len.de>, Yunsheng Lin <linyunsheng@...wei.com>,
Kuniyuki Iwashima <kuniyu@...zon.com>,
Arseniy Krasnov <avkrasnov@...utedevices.com>,
Aleksander Lobakin <aleksander.lobakin@...el.com>,
Michael Lass <bevan@...co.net>, Jiri Pirko <jiri@...nulli.us>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Lorenzo Bianconi <lorenzo@...nel.org>,
Richard Gobert <richardbgobert@...il.com>,
Sridhar Samudrala <sridhar.samudrala@...el.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Johannes Berg <johannes.berg@...el.com>, Abel Wu <wuyun.abel@...edance.com>,
Breno Leitao <leitao@...ian.org>, Pavel Begunkov <asml.silence@...il.com>,
Jason Gunthorpe <jgg@...pe.ca>, 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>,
linux-mm@...ck.org, Matthew Wilcox <willy@...radead.org>
Subject: Re: [RFC PATCH net-next v8 07/14] page_pool: devmem support
On 30/04/2024 20.55, Jens Axboe wrote:
> On 4/30/24 12:29 PM, Mina Almasry wrote:
>> On Tue, Apr 30, 2024 at 6:46?AM Jens Axboe<axboe@...nel.dk> wrote:
[...]
>>> In general, attempting to hide overhead behind config options is always
>>> a losing proposition. It merely serves to say "look, if these things
>>> aren't enabled, the overhead isn't there", while distros blindly enable
>>> pretty much everything and then you're back where you started.
>>>
>> The history there is that this check adds 1 cycle regression to the
>> page_pool fast path benchmark. The regression last I measured is 8->9
>> cycles, so in % wise it's a quite significant 12.5% (more details in
>> the cover letter[1]). I doubt I can do much better than that to be
>> honest.
>
> I'm all for cycle counting, and do it myself too, but is that even
> measurable in anything that isn't a super targeted microbenchmark? Or
> even in that?
The reason for page_pool fast path being critical is that it is used for
the XDP_DROP use-case.
E.g on Mellanox mlx5 driver we see 24 Mpps XDP_DROP, which is approx 42
nanosec per packet. Adding 9 nanosec will reduce this to 19.6 Mpps.
1/(42+9)*10^9 = 19607843
--Jesper
p.s. Upstreaming my PP microbenchmark[1] is still at the bottom of my
todo-list.
[1]
https://github.com/netoptimizer/prototype-kernel/blob/master/kernel/lib/bench_page_pool_simple.c
Powered by blists - more mailing lists