From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1522651574; cv=none; d=google.com; s=arc-20160816; b=bJZ1gqLyZWrbVPBkg4+ciehspcD6/Q6A2Y3/PyNSXP/Xb5hbfv4z3J1NkZrvi8ikeK 3IUMYWgIoZsGDO9/15ZuehKgjAKj3D3sWUYg7mCODX4CyGGLMj/fqNgp7/FblfoY1edg uuCJ1YyT297sUS7i0GeLropbKhZ/xWwm9hMSLcTzumdERsDoRL5MXqqH9GVzp7azhsXD ycCMwo2VDXtBddYqd6n4/m89m68E4AoDsPaOs7ZMGxT+9vG5MxS7vjz7eOPdxdeHGsUx htJwORB4bZ+bZZiwNTHUVJWnV/1EiN3zKWM0t7h+pvEm4VDF8XyXbAmvF9C+LF+v5oXY J0vQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to :mime-version:dkim-signature:arc-authentication-results; bh=1hfZy5K2fZ99yu5evPoFCgTHFEwpe/0snBed+Vb4XkE=; b=l7R09qTAMJNg0ftbnwCL0eiLF5/88O7brrzSoysGN8dK8misKx0Y4dDA6kgEDuXcqX KAglIh9JBE0U99rzXlPG5qJAwiAgGqJK3yLumSNdAMXdlyQSt+3j3xawNVEBhnnEEHeC yCQ/qboar/g4JqD4ZVUgUUl7ve1uSjrFci9b5qCzDn9K/EwCsX1pHXWct+qM26w8HOuY J4F4OCmWCKlPmFgfxMqT1P9cps8C4J9TEM8KjK/239jsu2WvfBtusX1yD5GQI8ZZeff+ zYsfjNIdSzGqBumBGzN7SlUAXLKrpqAtbWfDUfNQE7/CIF4ui8gU36kY7gnWIFlfx3il +V6w== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Xk4tYAE0; spf=pass (google.com: domain of opensource.ganesh@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=opensource.ganesh@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Xk4tYAE0; spf=pass (google.com: domain of opensource.ganesh@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=opensource.ganesh@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AIpwx49KW1p1A8Vydhq+jQ4sG9/u/dyG+5tv8L1QNxB2re/z9wxD7If5OFJMBr+bVMVtt914AO/IrO+Bdph3diYOREM= MIME-Version: 1.0 In-Reply-To: <20180402063448.GA250086@rodete-desktop-imager.corp.google.com> References: <20180329065424.203172-1-minchan@kernel.org> <20180330012921.GB255979@rodete-desktop-imager.corp.google.com> <20180330100407.GB19140@kroah.com> <20180402063448.GA250086@rodete-desktop-imager.corp.google.com> From: Ganesh Mahendran Date: Mon, 2 Apr 2018 14:46:14 +0800 Message-ID: Subject: Re: [PATCH v5] ANDROID: binder: change down_write to down_read To: Minchan Kim Cc: Greg Kroah-Hartman , LKML , Joe Perches , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Todd Kjos , Martijn Coenen Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1596254032587353794?= X-GMAIL-MSGID: =?utf-8?q?1596615897720555737?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 2018-04-02 14:34 GMT+08:00 Minchan Kim : > On Fri, Mar 30, 2018 at 12:04:07PM +0200, Greg Kroah-Hartman wrote: >> On Fri, Mar 30, 2018 at 10:29:21AM +0900, Minchan Kim wrote: >> > Hi Ganesh, >> > >> > On Fri, Mar 30, 2018 at 09:21:55AM +0800, Ganesh Mahendran wrote: >> > > 2018-03-29 14:54 GMT+08:00 Minchan Kim : >> > > > binder_update_page_range needs down_write of mmap_sem because >> > > > vm_insert_page need to change vma->vm_flags to VM_MIXEDMAP unless >> > > > it is set. However, when I profile binder working, it seems >> > > > every binder buffers should be mapped in advance by binder_mmap. >> > > > It means we could set VM_MIXEDMAP in binder_mmap time which is >> > > > already hold a mmap_sem as down_write so binder_update_page_range >> > > > doesn't need to hold a mmap_sem as down_write. >> > > > >> > > > Android suffers from mmap_sem contention so let's reduce mmap_sem >> > > > down_write. >> > > >> > > Hi, Minchan: >> > > >> > > It seems there is performance regression of this patch. >> > >> > You mean "This patch aims for solving performance regression" not "This patch >> > makes performance regression"? >> > >> > > >> > > Do you have some test result of android app launch time or binderThroughput? >> > >> > Unfortunately, I don't have any number. The goal is to reduce the number of >> > call mmap_sem as write-side lock because it makes priority inversion of threads >> > easily and that's one of clear part I spot that we don't need write-side lock. >> >> Please always run the binderThroughput tests when making binder changes >> (there is a binder test suite in the CTS Android tests), as that ensures >> that you are not causing performance regressions as well as just normal >> bug regressions :) > > Thanks for the information. I didn't notice that such kinds of tests for > binder. I will keep it in mind. > > Today, I have setup the testing for my phone and found testing was very > fluctuating even without my patch. It might be not good with my test > skill. I emulated user's behavior with various touch event. With it, I open > various apps and play with them several times. Before starting the test, > I did "adb shell stop && adb shell start && echo 3 > /proc/sys/vm/drop_caches" > > Such 15% noise was very easy to make it. > > Ganesh, How did you measure? What's the stddev? Hi, Minchan: Sorry for the late response, a little busy these days. :) We have our own test tools to measure app launch time, or you can use android systrace to get the app launch time. We tested your V1 patch: https://patchwork.kernel.org/patch/10312057/ and found app lunch time regression. I will use binderThroghput tool to test the patch today or tomorrow. Thanks. > Please let me know how you measure without noise so I'd like to reproduce > the result in my phone. > > I will do binderThroghput test, too. > >