From: Theodore Ts'o Subject: Re: Excessive stall times on ext4 in 3.9-rc2 Date: Mon, 8 Apr 2013 07:01:12 -0400 Message-ID: <20130408110112.GA8332@thunk.org> References: <20130402142717.GH32241@suse.de> <20130402150651.GB31577@thunk.org> <20130402151436.GC31577@thunk.org> <20130402181940.GA4936@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mel Gorman , linux-ext4@vger.kernel.org, LKML , Linux-MM , Jiri Slaby To: "Frank Ch. Eigler" Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:60234 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935282Ab3DHLCA (ORCPT ); Mon, 8 Apr 2013 07:02:00 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: On Sun, Apr 07, 2013 at 05:59:06PM -0400, Frank Ch. Eigler wrote: > > semantic error: while resolving probe point: identifier 'kprobe' at /tmp/stapdjN4_l:18:7 > > source: probe kprobe.function("get_request_wait") > > ^ > > Pass 2: analysis failed. [man error::pass2] > > Unexpected exit of STAP script at ./watch-dstate.pl line 296. > > I have no clue what to do next. Can you give me a hint? Is there any reason why the error message couldn't be simplified, to something as "kernel symbol not found"? I wasn't sure if the problem was that there was some incompatibility between a recent change with kprobe and systemtap, or parse failure in the systemtap script, etc. > Systemtap could endavour to list roughly-matching functions that do > exist, if you think that's be helpful. If the goal is ease of use, I suspect the more important thing that systemtap could do is to make its error messages more easily understandable, instead of pointing the user to read a man page where the user then has to figure out which one of a number of failure scenarios were caused by a particularly opaque error message. (The man page doesn't even say that "semantic error while resolving probe point" means that a kernel function doesn't exist -- especially complaining about the kprobe identifier points the user in the wrong direction.) - Ted