Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751919AbaBIV1n (ORCPT ); Sun, 9 Feb 2014 16:27:43 -0500 Received: from mx1.redhat.com ([209.132.183.28]:61241 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751691AbaBIV1l (ORCPT ); Sun, 9 Feb 2014 16:27:41 -0500 Date: Sun, 9 Feb 2014 16:27:24 -0500 From: "Frank Ch. Eigler" To: Ingo Molnar Cc: Masami Hiramatsu , linux-arch@vger.kernel.org, Ananth N Mavinakayanahalli , Sandeepa Prabhu , x86@kernel.org, lkml , "Steven Rostedt (Red Hat)" , systemtap@sourceware.org, "David S. Miller" Subject: Re: [PATCH -tip v6 00/22] kprobes: introduce NOKPROBE_SYMBOL(), cleanup and fixes crash bugs Message-ID: <20140209212724.GA6892@redhat.com> References: <20131219090353.14309.15496.stgit@kbuild-fedora.novalocal> <52B3C5E6.2040802@hitachi.com> <20131220082056.GA15934@gmail.com> <52B40E79.8040701@hitachi.com> <20131220104615.GA22609@gmail.com> <52E8E487.2090007@hitachi.com> <20140209143709.GA31608@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140209143709.GA31608@gmail.com> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi - > > So the similar thing happens when we enables events as below; > > > > # for i in /sys/kernel/debug/tracing/events/kprobes/* ; do date; echo 1 > $i; done > > Wed Jan 29 10:44:50 UTC 2014 > > ... > > > > I tried it and canceled after 4 min passed. It enabled about 17k > > events and slowed down my system very much(I almost got hang check > > timer). > > Ok, I guess that's the slowdown bug that Frank reported. It could be, but it feels a bit different. In my testing from December, it's as though it wasn't the activated probes *hitting* that were associated with the slowdown, but them merely being activated. It was as though something with the kprobes/ftrace probe-registration code performed a lot more work than it did longer ago. (One way to test this could be to be more careful in the selection of kprobes being enabled. For examle, emplace thousands, but only unused loaded modules.) I'm sorry I didn't get time to investigate further. - FChE -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/