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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E15D2C6FD1C for ; Sun, 26 Mar 2023 15:22:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231834AbjCZPWw (ORCPT ); Sun, 26 Mar 2023 11:22:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54874 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229621AbjCZPWv (ORCPT ); Sun, 26 Mar 2023 11:22:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DFE67284; Sun, 26 Mar 2023 08:22:50 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A150E60EF9; Sun, 26 Mar 2023 15:22:49 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75B10C433EF; Sun, 26 Mar 2023 15:22:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679844169; bh=jPU/1PkEjmLpuG/yzDwbE8MsDf1jHD5VOMCtE/4q5oc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=l+6tQbymSzTr6IS5BMRpGd5XX4HuYNdB8yFSqDlx1qkM8+ajHIhyB11NSAoyEi3X1 zsMtVyf/RD87g3xLIEcjT8Rw8oK7sksjCyLOWb4bnSyaFgi/4yJhQSD/DUqgLfYedC z7l43Imtg49EboK8X4ff1pDkxeKlccKwPIlE0f1uiPBIBTY2inebpqTus/toO2LFbw zt3SCtxf6O4usZlE2+E+C10tZBZNr8BQbOVL79tf1hj0APyBIMRluLfWD+KK/efO9I /3KmVvu1IQ9gaPZ98NCq83j+HnBbxc0rk7/a30FRo2xO0UpstqtDjo/s5Cpmy/4Uiu ZnBhbIpEKrhFQ== Date: Sun, 26 Mar 2023 23:22:42 +0800 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Beau Belgrave , Vlastimil Babka , "Masami Hiramatsu (Google)" , mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com, brauner@kernel.org, akpm@linux-foundation.org, ebiederm@xmission.com, keescook@chromium.org, tglx@linutronix.de, linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v8 11/11] tracing/user_events: Limit global user_event count Message-Id: <20230326232242.adb5ad253b3810aaf9686d2f@kernel.org> In-Reply-To: <20230324130659.587ecfd2@gandalf.local.home> References: <20230221211143.574-1-beaub@linux.microsoft.com> <20230221211143.574-12-beaub@linux.microsoft.com> <20230324081824.b917c2944da217e5239e1223@kernel.org> <20230324164353.GA1790@kbox> <20230324130659.587ecfd2@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-trace-devel@vger.kernel.org On Fri, 24 Mar 2023 13:06:59 -0400 Steven Rostedt wrote: > On Fri, 24 Mar 2023 09:43:53 -0700 > Beau Belgrave wrote: > > > > It was actually merged in 5.8. So sysctl should be sufficient with that. > > > But maybe it's weird to start adding sysctls, when the rest of tracing > > > tunables is AFAIK under /sys/kernel/tracing/ ? > > > > > > > During the TraceFS meetings Steven runs I was asked to add a boot > > parameter and sysctl for user_events to limit the max. > > > > To me, it seems when user_events moves toward namespace awareness > > sysctl might be easier to use from within a namespace to turn knobs. > > > > Happy to change to whatever, but I want to see Steven and Masami agree > > on the approach before doing so. > > > > Steven, do you agree with Masami to move to just sysctl? > > We do have some tracing related sysctls already: > > # cd /proc/sys/kernel > # ls *trace* > ftrace_dump_on_oops oops_all_cpu_backtrace traceoff_on_warning > ftrace_enabled stack_tracer_enabled tracepoint_printk > > Although I would love to deprecated ftrace_enable as that now has a > control in tracefs, but it's not unprecedented to have tracing tunables as > sysctl. > > And if we get cmdline boot parameters for free from sysctls then all the > better. Yeah, I confirmed that sysctl can be set via kernel parameter. So it is OK for me to add a sysctl. Thank you, > > -- Steve -- Masami Hiramatsu (Google)