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=-8.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL 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 C0BA7C31E5B for ; Tue, 18 Jun 2019 23:52:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86CAA20873 for ; Tue, 18 Jun 2019 23:52:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Hw8Wh065" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726007AbfFRXwg (ORCPT ); Tue, 18 Jun 2019 19:52:36 -0400 Received: from mail-qt1-f194.google.com ([209.85.160.194]:43044 "EHLO mail-qt1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725988AbfFRXwf (ORCPT ); Tue, 18 Jun 2019 19:52:35 -0400 Received: by mail-qt1-f194.google.com with SMTP id w17so11327080qto.10 for ; Tue, 18 Jun 2019 16:52:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=oxhoe6qvi5++Tcm34QYjpxvVrTyaf87PFGxTM5J5klQ=; b=Hw8Wh065g4/hqpkCuE2UUCCyaWWEgEqIivqSK4AXMEYZFcGFB/YyRBBxDQmwRa3/FK vzrp6nSLX89AZwg4NixpQRsHfSw4kAy/vNYqFDmj/46CvZOuY+rQNxJMLVTk76II5KMb 7StzCUc0Gk3xcASZ7v+85xbg/AmlBLI9C+bi9ajiUUpI3fVcCrRZ6DwQvtYgeYUDlBPr MSxYwTNzR3toM7Ww6JZCAh3CEWSG/y24xkrmjRk/f2aEuYaDg2F2XgGUTFD6ZEvOjCM6 ktrKNYaPkCfWbRCkJsQsHQE77KvMiB4JUel22BfKo02tDP2vLQW+VRL+Bw4EkzSCQLcQ WFbA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=oxhoe6qvi5++Tcm34QYjpxvVrTyaf87PFGxTM5J5klQ=; b=Y/YPPPiJxfRs6bk3aI2g6brIOp3y7Mrk43c2SpYOyM8VScuHaWzwMRtLkT0zkSIg1n PQ8VIjJKN9zsQfEzOmyy6p7rxRNrzMf34d1feo13WMLID8Bfvzxo58bflNAbrP1uGEXg lSxIJ0ModdIq+4zC5uZQhDzHLKOIJHj6Yi/aOatzgkvTcHMphXZ9/fdpbyMGrjhdV7fP 2IK5cu+dpq92CeyJmQDZw3DH9k9rgQPkSUsLg+FoFZwPR8j1mxo5326QGdyl5aAfkxMP F3pfUOF7EltTwlIaxa1Jzt4laCKZASlPai6MkzzqIl87ZtvSmOdmXPXzxH78r09/Z+Oj dwuA== X-Gm-Message-State: APjAAAXhSEVTd9+ardn+4ob0woYhV+RUTaPI3INnLwRUFv/CyVjigELi cjywwQ3cl1K5zlHM0EY8Mx9/OchQrPUlLBroDPwZaQ== X-Google-Smtp-Source: APXvYqwiv08J29plxlhYMIDWyxqgmuEcJ7gUaUt/etansUxZvljYL8gyykDyphwMNft4kHd5X4nMneBUhJsZemjwTmc= X-Received: by 2002:a0c:96c4:: with SMTP id b4mr29430317qvd.2.1560901954609; Tue, 18 Jun 2019 16:52:34 -0700 (PDT) MIME-Version: 1.0 References: <20190618182502.GC203031@google.com> <4587569.x9DSL43cXO@kreacher> In-Reply-To: From: Joel Fernandes Date: Tue, 18 Jun 2019 19:52:23 -0400 Message-ID: Subject: Re: Alternatives to /sys/kernel/debug/wakeup_sources To: Tri Vo Cc: "Rafael J. Wysocki" , Sandeep Patil , Viresh Kumar , Hridya Valsaraju , Linux PM , "Cc: Android Kernel" , Greg Kroah-Hartman , LKML Content-Type: text/plain; charset="UTF-8" Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Tue, Jun 18, 2019 at 7:15 PM Tri Vo wrote: [snip] > > > > > > > > > > Android userspace reading wakeup_sources is not ideal because: > > > > > - Debugfs API is not stable, i.e. Android tools built on top of it are > > > > > not guaranteed to be backward/forward compatible. > > > > > - This file requires debugfs to be mounted, which itself is > > > > > undesirable for security reasons. > > > > > > > > > > To address these problems, we want to contribute a way to expose these > > > > > statistics that doesn't depend on debugfs. > > > > > > > > > > Some initial thoughts/questions: Should we expose the stats in sysfs? > > > > > Or maybe implement eBPF-based solution? What do you think? > > > > > > We are going through Android's out-of-tree kernel dependencies along with > > > userspace APIs that are not necessarily considered "stable and forever > > > supported" upstream. The debugfs dependencies showed up on our radar as a > > > result and so we are wondering if we should worry about changes in debugfs > > > interface and hence the question(s) below. > > > > > > So, can we rely on /d/wakeup_sources to be considered a userspace API and > > > hence maintained stable as we do for other /proc and /sys entries? > > > > > > If yes, then we will go ahead and add tests for this in LTP or > > > somewhere else suitable. > > > > No, debugfs is not ABI. > > > > > If no, then we would love to hear suggestions for any changes that need to be > > > made or we simply just move the debugfs entry into somewhere like > > > /sys/power/ ? > > > > No, moving that entire file from debugfs into sysfs is not an option either. > > > > The statistics for the wakeup sources associated with devices are already there > > under /sys/devices/.../power/ , but I guess you want all wakeup sources? > > > > That would require adding a kobject to struct wakeup_source and exposing > > all of the statistics as separate attributes under it. In which case it would be > > good to replace the existing wakeup statistics under /sys/devices/.../power/ > > with symbolic links to the attributes under the wakeup_source kobject. > > Thanks for your input, Rafael! Your suggestion makes sense. I'll work > on a patch for this. Does that entail making each wake up source, a new sysfs node under a particular device, and then adding stats under that new node? thanks, - Joel