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 D9D4FC433F5 for ; Fri, 10 Dec 2021 17:43:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242037AbhLJRqo (ORCPT ); Fri, 10 Dec 2021 12:46:44 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:50000 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242020AbhLJRqo (ORCPT ); Fri, 10 Dec 2021 12:46:44 -0500 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 273D9B8294A; Fri, 10 Dec 2021 17:43:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CCACC00446; Fri, 10 Dec 2021 17:43:06 +0000 (UTC) Date: Fri, 10 Dec 2021 12:43:05 -0500 From: Steven Rostedt To: Masami Hiramatsu Cc: Beau Belgrave , linux-trace-devel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v7 02/13] user_events: Add minimal support for trace_event into ftrace Message-ID: <20211210124305.24acd61f@gandalf.local.home> In-Reply-To: <20211210194358.e590d49a1620df7345f9f679@kernel.org> References: <20211209223210.1818-1-beaub@linux.microsoft.com> <20211209223210.1818-3-beaub@linux.microsoft.com> <20211210194358.e590d49a1620df7345f9f679@kernel.org> 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, 10 Dec 2021 19:43:58 +0900 Masami Hiramatsu wrote: > > +/* Limit how long of an event name plus args within the subsystem. */ > > +#define MAX_EVENT_DESC 512 > > +#define EVENT_NAME(user_event) ((user_event)->tracepoint.name) > > +#define MAX_FIELD_ARRAY_SIZE (2 * PAGE_SIZE) > > I don't recommend to record the event which size is more than a page size... > Maybe 256 entries? > It is also better to limit the total size of the event and the number > of fields (arguments). > > Steve, can we write such a big event data on the trace buffer? In the future yes! https://lore.kernel.org/all/20211125175253.186422-1-tz.stoyanov@gmail.com/ But it will still require some configuration changes from user space. But that said, if the user wants to add a larger size, then they can do so (in the future). -- Steve