From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756788AbZJCBZc (ORCPT ); Fri, 2 Oct 2009 21:25:32 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756683AbZJCBZc (ORCPT ); Fri, 2 Oct 2009 21:25:32 -0400 Received: from mail-ew0-f211.google.com ([209.85.219.211]:57811 "EHLO mail-ew0-f211.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756656AbZJCBZb (ORCPT ); Fri, 2 Oct 2009 21:25:31 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=SeQpucRP2XXSUXr0OPxZSptshTrGrP2bDNFQFBoFhI86xwC1cJMZ4F+8bMEenZ8Ged FuZagqwSgpGniNYckhy2xjW0qjFcsIM2VlpPIhJ/XGSQNDJ1ugil6qOzPCjVQM/WCD8y wndSkNRQp/9YlJzPP8hQ+aQyf2B5GxnpcfgMY= Date: Sat, 3 Oct 2009 03:25:31 +0200 From: Frederic Weisbecker To: Masami Hiramatsu Cc: Steven Rostedt , Ingo Molnar , lkml , Thomas Gleixner , Arnaldo Carvalho de Melo , Mike Galbraith , Paul Mackerras , Peter Zijlstra , Christoph Hellwig , Ananth N Mavinakayanahalli , Jim Keniston , "Frank Ch. Eigler" , systemtap , DLE Subject: Re: [PATCH tracing/kprobes v2 0/5] tracing/kprobes, perf: perf probe support take 2 Message-ID: <20091003012528.GC4828@nowhere> References: <20091002214834.30906.86502.stgit@dhcp-100-2-132.bos.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091002214834.30906.86502.stgit@dhcp-100-2-132.bos.redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 02, 2009 at 05:48:34PM -0400, Masami Hiramatsu wrote: > Hi, > > These patches introduce 'perf probe' command and update kprobe-tracer. > perf probe command allows you to add new probe points by C line number > and local variable names. > > This version fixes some bugs, changes subcommand name from kprobe to > probe and use spaces for separator instead of ',' for visibility (this > also make it easy to support probe list from stdin). > > Usage > ----- > perf probe [] -P 'PROBEDEF' [-P 'PROBEDEF' ...] > > -k, --vmlinux vmlinux/module pathname > -r, --release kernel release > -P, --probe > probe point definition, where > p: kprobe probe > r: kretprobe probe > GRP: Group name (optional) > NAME: Event name > FUNC: Function name > OFFS: Offset from function entry (in byte) > SRC: Source code path > LINE: Line number > ARG: Probe argument (local variable name or > kprobe-tracer argument format is supported.) > > Examples > -------- > 1) Add a new kprobe probe on a line of C source code. > ./perf probe -P 'p:myprobe @fs/read_write.c:285 file buf count' > Adding new event: p:myprobe vfs_read+57 file=%bx buf=%si count=%ax Nice! Great thing. One neat, at a first glance, file=%bx buf=%si look like a format definition. How about using file=bx ? Or does that introduce any ambiguities with kprobes definitions syntax? > > 2) Add a new kretprobe probe on a function return. > ./perf probe -P 'r:myretprobe vfs_read $rv' > Adding new event: r:myretprobe vfs_read+0 $rv The '$' character may perhaps also confuse bash scripts that create perf probe. > 3) Check it in the perf list. > ./perf list > ... > rNNN [raw hardware event descriptor] > > kprobes:myprobe [Tracepoint event] > kprobes:myretprobe [Tracepoint event] > skb:kfree_skb [Tracepoint event] > ... > > 4) Record the event by perf > ./perf record -f -e kprobes:myprobe:record -F 1 -a ls > ... > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.081 MB perf.data (~3540 samples) ] > > 5) Trace the event > ./perf trace > perf-11445 [000] 95862.048894383: myprobe: (c04bbed5) file=dae15e80 buf=b78b2000 count=400 > perf-11445 [000] 95862.049066533: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400 > perf-11445 [000] 95862.049134394: myprobe: (c04bbed5) file=dae15d80 buf=b78b2000 count=400 > perf-11445 [000] 95862.049171495: myprobe: (c04bbed5) file=dae15a80 buf=b78b2000 count=400 > > NOTE > ---- > perf still fails to parse format if arguments have special charactors > (e.g. $rv, +10($sp) etc.) So, tracing myretprobe will fail with this > version. This will be solved by naming arguments automatically if it > doesn't have C-language name. > > TODO > ---- > - Support sys_perf_counter_open (non-root) Hmm, we really want it to be only usable by the root (except if the policy is tuned to allow that, but that's managed by perf already). > - Input from stdin/output to stdout > - Non-auto static variable > - Fields of data structures (var->field) > - Type support > - Bit fields > - Array (var[N]) > - Dynamic array indexing (var[var2]) > - String/dynamic arrays (var:string, var[N..M]) > - Force Type casting ((type)var) > - Non-inline search > - libdw, libdwfl > - etc. > > Thank you, > Cool, I'm reviewing/testing it and if no rough problem arise I'll apply it. Thanks a lot!