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=-1.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 7647FC2D0F7 for ; Tue, 12 May 2020 17:31:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E4C6206B8 for ; Tue, 12 May 2020 17:31:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1589304667; bh=No85bhKGDnXE3RujWoY9OPNvGoCJDkigbCNfGAGLfHU=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=NL/CukqfAC3a/+jq9LDMM342WuuQ0hlBpLhKmu2QzLMVvS41xPdYIE7mNXxIglqg5 QunRj25dPlh9zBguUhhTJtdDziZ20nTA4USQTgkXDB1ou0duO9bmKBf/NY8S1koBXp TZB0P236JVzoFmXzvfUF8E6zNBnPsBUZxqm5F41E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729505AbgELRbG (ORCPT ); Tue, 12 May 2020 13:31:06 -0400 Received: from mail-oo1-f67.google.com ([209.85.161.67]:42105 "EHLO mail-oo1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725554AbgELRbG (ORCPT ); Tue, 12 May 2020 13:31:06 -0400 Received: by mail-oo1-f67.google.com with SMTP id a83so1071528oob.9; Tue, 12 May 2020 10:31:04 -0700 (PDT) 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=j1rDBr2LZPsItx6oTianrE8hsJBryJBqNpicNCJ+hAs=; b=EhPKR/NRP0RukIDkdCDVe3PHbRB7rudpt1ez+EE+x6j8lqDdHDAWN4j0gDSdEa8xhp 5CCIT4b4rTnFCHxd2GpT09RqZ2FtTj9NqRaYkVSN1tcwJvUpMYQ+Ns9xutb6Ngb3W6CY 2ETqbsfQDW13qJQYFMFxm5/VqrVdRMC8i5jNRaFgTOzLX/9PsfUSnr4I4W3c43FyCFjX be0JwPk88TyoUPOWkRZnig1vs/JpOsJrlp18KmU5/yPZJF0d/2BliB+WDn0rKfeUASqi MiWevFYPZPMdJ/j2I4PVUSENJecK5gjby7Gh3jkwq7QtVJDzgTqLVMG0Vz+2+teR5QAs h3SQ== X-Gm-Message-State: AGi0PuYzJ3vZgS4KoiX6B8rKUT3Xtfe/TtExxSRj35rPpRbDltZ38Hif i7tUquX1Qf+pmwckJzpICk35EJSnhOwhWIs0KWY= X-Google-Smtp-Source: APiQypKndO1ilammFSxfSHkTTuvKf8k/4MMjBYODJ6DRYHfCIGjbXnCB2909MoBJph27lwy/hs1h5J+csCpw8WUFqGI= X-Received: by 2002:a4a:a286:: with SMTP id h6mr18757126ool.38.1589304663700; Tue, 12 May 2020 10:31:03 -0700 (PDT) MIME-Version: 1.0 References: <20200508130507.GA10541@google.com> <20200511090049.GA229633@google.com> <20200512092102.GA16151@google.com> <20200512135813.GA101124@google.com> <20200512151120.GB101124@google.com> <20200512162630.GC101124@google.com> In-Reply-To: <20200512162630.GC101124@google.com> From: "Rafael J. Wysocki" Date: Tue, 12 May 2020 19:30:52 +0200 Message-ID: Subject: Re: [PATCH 00/14] Modularize schedutil To: Quentin Perret Cc: "Rafael J. Wysocki" , Peter Zijlstra , Greg KH , Linux Kernel Mailing List , Linux PM , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "the arch/x86 maintainers" , "H. Peter Anvin" , Sudeep Holla , Viresh Kumar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Benjamin Segall , Mel Gorman , "Luis R. Rodriguez" , Kees Cook , Iurii Zaikin , Frederic Weisbecker , Todd Kjos , "Cc: Android Kernel" Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 12, 2020 at 6:26 PM Quentin Perret wrote: > > On Tuesday 12 May 2020 at 17:30:36 (+0200), Rafael J. Wysocki wrote: > > On Tue, May 12, 2020 at 5:11 PM Quentin Perret wrote: > > > The end goal with GKI is the following: Google will release a single > > > binary kernel image (signed, etc etc) that all devices using a given > > > Android version will be required to use. That image is however going to > > > be only for the core of the kernel (no drivers or anything of the sort). > > > Vendors and OEMs, on their end, will be responsible to build and ship > > > GKI-compatible modules for their respective devices. So, Android devices > > > will eventually ship with a Google-issued GKI, plus a bunch of > > > vendor-provided modules loaded during boot. > > > > If that is the case, then I absolutely think that schedutil should be > > part of the GKI. > > > > Moreover, that would have been my opinion even if it had been modular > > in the first place. > > I definitely understand the feeling. Heck I contributed to schedutil, so > I'd love to see the entire world run it :-) > > But my personal preference doesn't seem to matter in this world, sadly. > The truth is, we cannot afford to be arbitrary in our decisions in GKI. > Switching governors and such is a fully supported feature upstream, and > it has been for a long time. Taking that away from partners is not the > goal, nor the intention, of GKI. It still will be possible with schedutil built-in, however. > They will be able to choose whatever > governor they want, because there are no *objective* reasons to not let > them do that. Which, again, is still possible with non-modular schedutil AFAICS. I don't see any technical reason for making schedutil modular in the context of GKI other than to make the GKI image smaller, but I don't expect that to be significant enough. Is there anything else I am missing? > > > This is a significant shift from the current model where vendors > > > completely own the kernel, and are largely free to use the kernel config > > > they want. Today, those who don't use schedutil are free to turn the > > > config off, for example. > > > > So why is this regarded as a good thing? > > You mean using something else than schedutil? I mean why allowing people to compile schedutil out is regarded as a good thing. > It is not seen as a good > thing at all, at least not by me. But we have the same problem as > upstream. We cannot remove the other governors or the governor API for a > simple reason: they have users :/ I'm not saying about removing any of that. I'm just trying to understand why you need schedutil to be modular so as to make those things possible. Cheers!