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 63C24C433FE for ; Tue, 15 Nov 2022 03:03:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232390AbiKODDc convert rfc822-to-8bit (ORCPT ); Mon, 14 Nov 2022 22:03:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237795AbiKODCs (ORCPT ); Mon, 14 Nov 2022 22:02:48 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F234DF50 for ; Mon, 14 Nov 2022 19:01:36 -0800 (PST) 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 8BCF061520 for ; Tue, 15 Nov 2022 03:01:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09166C433C1; Tue, 15 Nov 2022 03:01:34 +0000 (UTC) Date: Mon, 14 Nov 2022 22:02:16 -0500 From: Steven Rostedt To: Jianlin Lv Cc: alison.schofield@intel.com, davidgow@google.com, thunder.leizhen@huawei.com, jianlv@ebay.com, linux-kernel@vger.kernel.org, Masami Hiramatsu Subject: Re: [PATCH] tracepoint: Allow livepatch module add trace event Message-ID: <20221114220216.05dd0541@gandalf.local.home> In-Reply-To: References: <20221102160236.11696-1-iecedge@gmail.com> <20221114122255.72588f45@gandalf.local.home> 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=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 15 Nov 2022 10:38:34 +0800 Jianlin Lv wrote: > On Tue, Nov 15, 2022 at 1:22 AM Steven Rostedt wrote: > > > > On Wed, 2 Nov 2022 16:02:36 +0000 > > Jianlin Lv wrote: > > > > > In the case of keeping the system running, the preferred method for > > > tracing the kernel is dynamic tracing (kprobe), but the drawback of > > > this method is that events are lost, especially when tracing packages > > > in the network stack. > > > > I'm not against this change, but the above is where I'm a bit confused. How > > are events more likely to be lost with kprobes over a static event? > > We have encountered a case of kprobes missing event, detailed > information can refer to the following link: > https://github.com/iovisor/bcc/issues/4198 > > Replacing kprobe with ’bpf + raw tracepoint‘, no missing events occur. > Masami, What's the reason that kprobes are not re-entrant when using ftrace? -- Steve