netdev - Re: [RFC PATCH net-next v6 00/15] Device Memory TCP

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 for Android: free password hash cracker in your pocket

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

Message-ID: <6208950d-6453-e797-7fc3-1dcf15b49dbe@huawei.com>
Date: Tue, 5 Mar 2024 20:54:42 +0800
From: Yunsheng Lin <linyunsheng@...wei.com>
To: Mina Almasry <almasrymina@...gle.com>, <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>
CC: "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>, 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>,
	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>, Pavel Begunkov <asml.silence@...il.com>, David
 Wei <dw@...idwei.uk>, Jason Gunthorpe <jgg@...pe.ca>, Shailend Chand
	<shailend@...gle.com>, Harshitha Ramamurthy <hramamurthy@...gle.com>, Shakeel
 Butt <shakeelb@...gle.com>, Jeroen de Borst <jeroendb@...gle.com>, Praveen
 Kaligineedi <pkaligineedi@...gle.com>
Subject: Re: [RFC PATCH net-next v6 00/15] Device Memory TCP

On 2024/3/5 10:01, Mina Almasry wrote:

...

> 
> Perf - page-pool benchmark:
> ---------------------------
> 
> bench_page_pool_simple.ko tests with and without these changes:
> https://pastebin.com/raw/ncHDwAbn
> 
> AFAIK the number that really matters in the perf tests is the
> 'tasklet_page_pool01_fast_path Per elem'. This one measures at about 8
> cycles without the changes but there is some 1 cycle noise in some
> results.
> 
> With the patches this regresses to 9 cycles with the changes but there
> is 1 cycle noise occasionally running this test repeatedly.
> 
> Lastly I tried disable the static_branch_unlikely() in
> netmem_is_net_iov() check. To my surprise disabling the
> static_branch_unlikely() check reduces the fast path back to 8 cycles,
> but the 1 cycle noise remains.
> 

The last sentence seems to be suggesting the above 1 ns regresses is caused
by the static_branch_unlikely() checking?