From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 215CAC4345F for ; Wed, 1 May 2024 13:59:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 4033E6B0088; Wed, 1 May 2024 09:59:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3B1E06B0089; Wed, 1 May 2024 09:59:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 279806B008A; Wed, 1 May 2024 09:59:21 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 0C2076B0088 for ; Wed, 1 May 2024 09:59:21 -0400 (EDT) Received: from smtpin21.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id AE1AE1C0F26 for ; Wed, 1 May 2024 13:59:20 +0000 (UTC) X-FDA: 82069984080.21.EE04ACD Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf02.hostedemail.com (Postfix) with ESMTP id 1D78B8000B for ; Wed, 1 May 2024 13:59:17 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sCbrUaES; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of hawk@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=hawk@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1714571958; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=gOze/2fzXHO/81tG2YTfo5sSZRKuFMGwh2n6uNRkncs=; b=M9UmObJHWUr9mS448+MTitflplaj7/leESqgVrbvpvXTZPLFgg0K3pxyH2vOiBZ0OEX0jy DG9jR/gzR6R3cbhDn9LJzKDBiGuVcn3C6/risxEbLNRNfs0rQOwQvIej/TAmUfnusbGmgz b7LtIkMUu+80tudSXhDCb03Hci5h17o= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=sCbrUaES; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf02.hostedemail.com: domain of hawk@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=hawk@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1714571958; a=rsa-sha256; cv=none; b=BoOkRnfa0qilrRdqUG2hqwxMY+208dYJQDgMEDUEMuZ6w9lcKG2ZbpMQtM6uN1Td0gyCwM skcNyS4Nh+TJbuf8jAHq/S8Ao4ewdY5mpFLY8Fgj/RXKtwsuzOSm/RzorB0rWSzgIMAIEk KXSCBGTFkLTHJPnS8FZfgK1ND7ecpaY= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 9FD3460AF6; Wed, 1 May 2024 13:59:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5B3C7C072AA; Wed, 1 May 2024 13:59:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1714571956; bh=Fi4PvMRZrF9DXNpSOwwia/BblzTiRO6iyf1z/eVq1XU=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=sCbrUaESax+zNwmTNdY7otL0UFOQLPT1tCLvxhS1E2UCWFKHW4CFOG8eHXGAPEzYV K59HSeGnESqWuVyypeDsfjxCGIwlrkTiIB8RtlSIeODJISpG+bjrjqgUZTNnVYoXFo 0nAjOD3kay/wsGxmwOPaAc5VD0eUhuiBlauj3Z2WQisvO7reiDxOn7qiXguQyswbXz eGzZQLUgdh76hRrtTEFJVQdEHnMA2UjgtwHVl2z9L4Tsb3ZTSE/wBE57PdTiTs8Ocp FhNUI+PSuIOyAwwjpVUsbAi1uNR+QWMI+7HqtFjSwPStPFYwbkZKYGKHcbZk0YZOQW CZlqUKG4oenXA== Message-ID: <779b9542-4170-483a-af54-ca0dd471f774@kernel.org> Date: Wed, 1 May 2024 15:58:59 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH net-next v8 07/14] page_pool: devmem support To: Jens Axboe , Mina Almasry Cc: David Wei , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-alpha@vger.kernel.org, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, sparclinux@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-arch@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Jonathan Corbet , Richard Henderson , Ivan Kokshaysky , Matt Turner , Thomas Bogendoerfer , "James E.J. Bottomley" , Helge Deller , Andreas Larsson , Ilias Apalodimas , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Steffen Klassert , Herbert Xu , David Ahern , Willem de Bruijn , Shuah Khan , Sumit Semwal , =?UTF-8?Q?Christian_K=C3=B6nig?= , Amritha Nambiar , Maciej Fijalkowski , Alexander Mikhalitsyn , Kaiyuan Zhang , Christian Brauner , Simon Horman , David Howells , Florian Westphal , Yunsheng Lin , Kuniyuki Iwashima , Arseniy Krasnov , Aleksander Lobakin , Michael Lass , Jiri Pirko , Sebastian Andrzej Siewior , Lorenzo Bianconi , Richard Gobert , Sridhar Samudrala , Xuan Zhuo , Johannes Berg , Abel Wu , Breno Leitao , Pavel Begunkov , Jason Gunthorpe , Shailend Chand , Harshitha Ramamurthy , Shakeel Butt , Jeroen de Borst , Praveen Kaligineedi , linux-mm@kvack.org, Matthew Wilcox References: <20240403002053.2376017-1-almasrymina@google.com> <20240403002053.2376017-8-almasrymina@google.com> <8357256a-f0e9-4640-8fec-23341fc607db@davidwei.uk> <11f52113-7b67-4b45-ba1d-29b070050cec@kernel.dk> Content-Language: en-US From: Jesper Dangaard Brouer In-Reply-To: <11f52113-7b67-4b45-ba1d-29b070050cec@kernel.dk> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: iyp9m584zay7ygn9aq8qmaf47o4dqyyq X-Rspam-User: X-Rspamd-Queue-Id: 1D78B8000B X-HE-Tag: 1714571957-279210 X-HE-Meta: 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 6cDzLonU Thg2l7STlmNxDY7VCNfDI6/JGhEvovLtW1WIaCFpfUMr2PLsUsVWHRzwv7GWQmRm/tQpS3uuvffGnhDU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 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