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 DAF51C6FD1C for ; Fri, 24 Mar 2023 17:07:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230267AbjCXRHI (ORCPT ); Fri, 24 Mar 2023 13:07:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57004 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231346AbjCXRHH (ORCPT ); Fri, 24 Mar 2023 13:07:07 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9C7A18B2C; Fri, 24 Mar 2023 10:07:05 -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 ams.source.kernel.org (Postfix) with ESMTPS id 6E8E7B822D8; Fri, 24 Mar 2023 17:07:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A11E8C433EF; Fri, 24 Mar 2023 17:07:01 +0000 (UTC) Date: Fri, 24 Mar 2023 13:06:59 -0400 From: Steven Rostedt To: Beau Belgrave Cc: 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: <20230324130659.587ecfd2@gandalf.local.home> In-Reply-To: <20230324164353.GA1790@kbox> References: <20230221211143.574-1-beaub@linux.microsoft.com> <20230221211143.574-12-beaub@linux.microsoft.com> <20230324081824.b917c2944da217e5239e1223@kernel.org> <20230324164353.GA1790@kbox> X-Mailer: Claws Mail 3.17.8 (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 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. -- Steve