From: fche@redhat.com (Frank Ch. Eigler) Subject: Re: Excessive stall times on ext4 in 3.9-rc2 Date: Sun, 07 Apr 2013 17:59:06 -0400 Message-ID: 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: "Theodore Ts'o" Return-path: In-Reply-To: <20130402181940.GA4936@thunk.org> (Theodore Ts'o's message of "Tue, 2 Apr 2013 14:19:40 -0400") Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org Hi - tytso wrote: > So I tried to reproduce the problem, and so I installed systemtap > (bleeding edge, since otherwise it won't work with development > kernel), and then rebuilt a kernel with all of the necessary CONFIG > options enabled: > > CONFIG_DEBUG_INFO, CONFIG_KPROBES, CONFIG_RELAY, CONFIG_DEBUG_FS, > CONFIG_MODULES, CONFIG_MODULE_UNLOAD > [...] That sounds about right. > I then pulled down mmtests, and tried running watch-dstate.pl, which > is what I assume you were using [...] I just took a look at the mmtests, particularly the stap-fix.sh stuff. The heroics therein are really not called for. git kernel developers should use git systemtap, as has always been the case. All compatibility hacks in stap-fix.sh have already been merged, in many cases for months. > [...] > 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? You should see the error::pass2 man page, which refers to error::reporting, which refers to involving stap folks and running stap-report to gather needed info. But in this case, that's unnecessary: the problem is most likely that the get_request_wait function does not actually exist any longer, since commit a06e05e6afab70b4b23c0a7975aaeae24b195cd6 Author: Tejun Heo Date: Mon Jun 4 20:40:55 2012 -0700 block: refactor get_request[_wait]() Systemtap could endavour to list roughly-matching functions that do exist, if you think that's be helpful. - FChE