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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 D4AD1C10DCE for ; Fri, 6 Mar 2020 23:10:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A7FD7206E2 for ; Fri, 6 Mar 2020 23:10:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="LulrOrqp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726704AbgCFXKc (ORCPT ); Fri, 6 Mar 2020 18:10:32 -0500 Received: from mail-lf1-f66.google.com ([209.85.167.66]:33045 "EHLO mail-lf1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726237AbgCFXKc (ORCPT ); Fri, 6 Mar 2020 18:10:32 -0500 Received: by mail-lf1-f66.google.com with SMTP id c20so3240756lfb.0; Fri, 06 Mar 2020 15:10:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Qe8wUFv1rWfO0Jj+EAuF6LQPlbPXK3Z6EOrgI0Gdx9k=; b=LulrOrqpx0/0G8hFYqFzxTYNXXW1JCsFHC320W5pxat1R/Gq10mUIexXFg2X0IjgkH R/8OhsWZREwdNq+pWnetJCN+wKY6PPWO7dlynTtYJFZLdrxNLmuvOkDAxdvIqtMfa5Pf SNsnvvVnhVemr+T/5x7OgVlT89LwffGVOAG3Kgl/Qk6tX4RwNOAgMKPi67hqLUslbQpd FWE6uU0yvEXZRKex0XGHlyDOzviTBdAyQl1dH+YWCS9YJG9oNNCaXTXIbmDewUqRKY7N yGRAGMRJms0Yc3KcFiF3OJg4QbEE4Jg4HxqFtz9uiU5Qd3B82bawpm43rnyZe0QSVjMT BuPw== 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=Qe8wUFv1rWfO0Jj+EAuF6LQPlbPXK3Z6EOrgI0Gdx9k=; b=KCyZKLhJbCNBYIQCKd2ReG5OvD08oUk9LtFQF6dCaJHaUZUe0JN9JnWIbPC4zRsATo ZugppOY6e+iyHuIUvhR4zpT9RJutZpqRVYsKpkmD05bkHtb0g68eRGHUZt9Zrf1E9jJ6 tS2qeMg6O3uTYothNo4O0Jl7iZITgBWV8mfElYC/59y3wdMVc1nKYpYrKEgywB64Y5z2 +pau6BZuDI/Vw1oPhHrpyavFvMKbxorEx5tmdElF/bn5oC6txiZ6Fmat6LRoQFueufnc Ik2HKt3GuLsWPcMZHIN3x0KvsswtLu7pj4p19uw0VhPqmP50pJf+ESLnuiCA8ec55c4r qJtA== X-Gm-Message-State: ANhLgQ0gXqdtqcgVmOH6ij6+NilG1FM6sH7ASdGJTm2+z+UH01HY/z3u e7IBsZGOJk3Inv8uEGt7kgWBkCRA68fYJUuGWJ4= X-Google-Smtp-Source: ADFU+vsWXcoIQAUDTax0XOY1RpvoM6JRnIfSwIJuQvEjIepHZNV7DI+yPeXZlM2SlMk1yIeSgf5HOkbcz+PE0R5Ub0o= X-Received: by 2002:a05:6512:304c:: with SMTP id b12mr3256481lfb.196.1583536229276; Fri, 06 Mar 2020 15:10:29 -0800 (PST) MIME-Version: 1.0 References: <20200221133416.777099322@infradead.org> <20200306104335.GF3348@worktop.programming.kicks-ass.net> <20200306113135.GA8787@worktop.programming.kicks-ass.net> <1896740806.20220.1583510668164.JavaMail.zimbra@efficios.com> <20200306125500.6aa75c0d@gandalf.local.home> <609624365.20355.1583526166349.JavaMail.zimbra@efficios.com> <20200306154556.6a829484@gandalf.local.home> <65796626.20397.1583528124078.JavaMail.zimbra@efficios.com> In-Reply-To: <65796626.20397.1583528124078.JavaMail.zimbra@efficios.com> From: Alexei Starovoitov Date: Fri, 6 Mar 2020 15:10:17 -0800 Message-ID: Subject: Re: [PATCH v4 16/27] tracing: Remove regular RCU context for _rcuidle tracepoints (again) To: Mathieu Desnoyers Cc: rostedt , Peter Zijlstra , linux-kernel , linux-arch , Ingo Molnar , "Joel Fernandes, Google" , Greg Kroah-Hartman , "Gustavo A. R. Silva" , Thomas Gleixner , paulmck , Josh Triplett , Lai Jiangshan , Andy Lutomirski , Tony Luck , Frederic Weisbecker , dan carpenter , Masami Hiramatsu 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 Fri, Mar 6, 2020 at 12:55 PM Mathieu Desnoyers wrote: > > ----- On Mar 6, 2020, at 3:45 PM, rostedt rostedt@goodmis.org wrote: > > > On Fri, 6 Mar 2020 15:22:46 -0500 (EST) > > Mathieu Desnoyers wrote: > > > >> I agree with the overall approach. Just a bit of nitpicking on the API: > >> > >> I understand that the "prio" argument is a separate argument because it can take > >> many values. However, "rcu" is just a boolean, so I wonder if we should not > >> rather > >> introduce a "int flags" with a bitmask enum, e.g. > > > > I thought about this approach, but thought it was a bit overkill. As the > > kernel doesn't have an internal API, I figured we can switch this over to > > flags when we get another flag to add. Unless you can think of one in the > > near future. > > The additional feature I have in mind for near future would be to register > a probe which can take a page fault to a "sleepable" tracepoint. This would > require preemption to be enabled and use of SRCU. I'm working on sleepable bpf as well and this extra flag for tracepoints would come very handy, so I would go with flags approach right away. We wouldn't need to touch the same protos multiple times, less conflicts for us all, etc.