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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65CF1C433DF for ; Sun, 7 Jun 2020 01:13:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2ACE02067B for ; Sun, 7 Jun 2020 01:13:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=themaw.net header.i=@themaw.net header.b="Ex5vAyC/"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Vxp8+2V8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728899AbgFGBNU (ORCPT ); Sat, 6 Jun 2020 21:13:20 -0400 Received: from new2-smtp.messagingengine.com ([66.111.4.224]:50831 "EHLO new2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728723AbgFGBNT (ORCPT ); Sat, 6 Jun 2020 21:13:19 -0400 Received: from compute2.internal (compute2.nyi.internal [10.202.2.42]) by mailnew.nyi.internal (Postfix) with ESMTP id 7CF9D5800A6; Sat, 6 Jun 2020 21:13:18 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Sat, 06 Jun 2020 21:13:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=themaw.net; h= message-id:subject:from:to:cc:date:in-reply-to:references :content-type:mime-version:content-transfer-encoding; s=fm3; bh= EjdSuTw7ySjJ1wbQSxC6dke+Hnj5woSaxhQn7kq2flA=; b=Ex5vAyC/n8rzrJN6 p0/LZCi5QquXfoa5YOGeQoB5qYHO/GJQfOmAUSFbOXLeKY3aenQg5RngL/o4bOaW nD+cZxK2gqe1VsPGezsGpyBiVhjNerAH9AkyP/+t4b1bEZtY5kHMdzQ6YqNf6Z44 A29Ntk8IiS+4MqhfiDhf0FP6tPfFnSkJ8/KoR/oCspdJ798UwLcc8ly020jpTkEO /Mz8t7lov4SC0UT5AuyNskizEhBkeCVSCVMN9TtMP9Sn9MILs3FRTCSOx6G2aPh9 LcSfaHAHC1MYRDhJyx5Z9QX1CLu4JskUaMH/uE5R6/PpZ7CIhAYiSMBXiGbDbAdg Q4xjzQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; bh=EjdSuTw7ySjJ1wbQSxC6dke+Hnj5woSaxhQn7kq2f lA=; b=Vxp8+2V85iqVaOn5cQdeUU5NvmdbmZBAEvcS7i74MBKCo7VV9UAQ7W1+0 5moU0hxWlSGwB9Tq8QPKZS3xvVW56mwLLJa2SWc3lvOp16PYXMUlzTOw8zFJAQ9p 8tAUPhk8OIDgw0Yj7t0MIsWiawO4rYIu4KTInOXWQsrLFlopvmEvzrmFjJxX/xTc oEtwH1CIJQBpA+LIQJQ1TQr1h9lz4RmleiFsK/BLToayDXYsq7jo94LnKIXyAFes H6yFZR4Am7cm+ecIUzRhDp5BiluVgxVmuRkjM5aO3d49LHjbSpX5Rv87GbWkwUG8 pW4GskM6seO/qaGe0lrvW21DjtE9w== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduhedrudegjedgudehucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhepkffuhffvffgjfhgtfggggfesthejredttderjeenucfhrhhomhepkfgrnhcu mfgvnhhtuceorhgrvhgvnhesthhhvghmrgifrdhnvghtqeenucggtffrrghtthgvrhhnpe ekkeejieeiieegvedvvdejjeegfeffleekudekgedvudeggeevgfekvdfhvdelfeenucff ohhmrghinhepghhithhhuhgsrdgtohhmnecukfhppeehkedrjedrvddvtddrgeejnecuve hluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomheprhgrvhgvnhes thhhvghmrgifrdhnvght X-ME-Proxy: Received: from mickey.themaw.net (58-7-220-47.dyn.iinet.net.au [58.7.220.47]) by mail.messagingengine.com (Postfix) with ESMTPA id 92A18328005D; Sat, 6 Jun 2020 21:13:12 -0400 (EDT) Message-ID: <5df6bec6f1b332c993474782c08fe8db30bffddc.camel@themaw.net> Subject: Re: [kernfs] ea7c5fc39a: stress-ng.stream.ops_per_sec 11827.2% improvement From: Ian Kent To: Greg Kroah-Hartman , kernel test robot Cc: Andrew Morton , Al Viro , Tejun Heo , Rick Lindsley , Stephen Rothwell , David Howells , Miklos Szeredi , linux-fsdevel , Kernel Mailing List , lkp@lists.01.org Date: Sun, 07 Jun 2020 09:13:08 +0800 In-Reply-To: <20200606181802.GA15638@kroah.com> References: <159038562460.276051.5267555021380171295.stgit@mickey.themaw.net> <20200606155216.GU12456@shao2-debian> <20200606181802.GA15638@kroah.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2020-06-06 at 20:18 +0200, Greg Kroah-Hartman wrote: > On Sat, Jun 06, 2020 at 11:52:16PM +0800, kernel test robot wrote: > > Greeting, > > > > FYI, we noticed a 11827.2% improvement of stress- > > ng.stream.ops_per_sec due to commit: > > > > > > commit: ea7c5fc39ab005b501e0c7666c29db36321e4f74 ("[PATCH 1/4] > > kernfs: switch kernfs to use an rwsem") > > url: > > https://github.com/0day-ci/linux/commits/Ian-Kent/kernfs-proposed-locking-and-concurrency-improvement/20200525-134849 > > > > Seriously? That's a huge performance increase, and one that feels > really odd. Why would a stress-ng test be touching sysfs? That is unusually high even if there's a lot of sysfs or kernfs activity and that patch shouldn't improve VFS path walk contention very much even if it is present. Maybe I've missed something, and the information provided doesn't seem to be quite enough to even make a start on it. That's going to need some analysis which, for my part, will need to wait probably until around rc1 time frame to allow me to get through the push down stack (reactive, postponed due to other priorities) of jobs I have in order to get back to the fifo queue (longer term tasks, of which this is one) list of jobs I need to do as well, ;) Please, kernel test robot, more information about this test and what it's doing. Ian