From mboxrd@z Thu Jan 1 00:00:00 1970 From: Masami Hiramatsu Subject: Re: [PATCH -tip v6 00/22] kprobes: introduce NOKPROBE_SYMBOL(), cleanup and fixes crash bugs Date: Tue, 24 Dec 2013 10:19:01 +0900 Message-ID: <52B8E105.90908@hitachi.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> <52B75542.7040600@hitachi.com> <20131223130438.GA5076@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mail4.hitachi.co.jp ([133.145.228.5]:39912 "EHLO mail4.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753637Ab3LXBTM (ORCPT ); Mon, 23 Dec 2013 20:19:12 -0500 In-Reply-To: <20131223130438.GA5076@gmail.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Ingo Molnar Cc: "Frank Ch. Eigler" , linux-arch@vger.kernel.org, Ananth N Mavinakayanahalli , Sandeepa Prabhu , x86@kernel.org, lkml , "Steven Rostedt (Red Hat)" , systemtap@sourceware.org, "David S. Miller" (2013/12/23 22:04), Ingo Molnar wrote: > > * Masami Hiramatsu wrote: > >>> I can reproduce one weirdness, with just 13 probes added, 'perf probe >>> -l' [which should really be 'perf probe list'!] executes very slowly: >>> >>> # perf stat --null --repeat 3 perf probe -l >>> >>> Performance counter stats for 'perf probe -l' (3 runs): >>> >>> 0.763640098 seconds time elapsed ( +- 1.61% ) >>> >>> 0.7 seconds is ridiculously long. >> >> This comes from the perf-probe's internal issue. It tries to get >> actual lines and files by using debuginfo. I guess most of the time >> consumed when processing huge kernel debuginfo. > > No, I don't have any debuginfo, I never use it. Then it should be a performance bug. I need to take a look. BTW, this is just a bug of perf probe, for example, # wc -l /sys/kernel/debug/tracing/kprobe_events 3204 /sys/kernel/debug/tracing/kprobe_events # ./perf stat --null --repeat 3 cat /sys/kernel/debug/tracing/kprobe_events Performance counter stats for 'cat /sys/kernel/debug/tracing/kprobe_events' (3 runs): 0.032075943 seconds time elapsed ( +- 38.72% ) So even with 3204 probes, listing the kprobe events only takes 0.03 sec. Thank you, -- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com