From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751401AbWJMRp6 (ORCPT ); Fri, 13 Oct 2006 13:45:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751495AbWJMRp6 (ORCPT ); Fri, 13 Oct 2006 13:45:58 -0400 Received: from py-out-1112.google.com ([64.233.166.177]:29163 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S1751401AbWJMRp5 (ORCPT ); Fri, 13 Oct 2006 13:45:57 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:date:from:to:cc:subject:message-id:mail-followup-to:references:mime-version:content-type:content-disposition:in-reply-to:user-agent; b=Yr+ZWAJq+IPhbX4Tjm5v8g2AnExE8FartSG7OfT7KQmkJEwKEWbL5ezn73mhd94TAXTHCHQ4PpEZS/31XjZwZlAiWU/79ChMY8pWWmQYKdTHmO5lhxKoQoCQ98zIksyWz79crYDPhkbbb1gut/2J/XFLjFaZ9bkrOvPVgfBqYq8= Date: Sat, 14 Oct 2006 02:46:24 +0900 From: Akinobu Mita To: Andrew Morton Cc: linux-kernel@vger.kernel.org, ak@suse.de, Don Mullis Subject: Re: [patch 0/7] fault-injection capabilities (v5) Message-ID: <20061013174623.GA29079@localhost> Mail-Followup-To: Akinobu Mita , Andrew Morton , linux-kernel@vger.kernel.org, ak@suse.de, Don Mullis References: <452df20e.025ef312.44f0.7578@mx.google.com> <20061012142625.520d3d87.akpm@osdl.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061012142625.520d3d87.akpm@osdl.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 12, 2006 at 02:26:25PM -0700, Andrew Morton wrote: > You've presumably run a kernel with these various things enabled. What > happens? Does the kernel run really slowly? Does userspace collapse in a > heap? Does it oops and die? I don't feel much slowness with STACKTRACE & FRAME_POINTER and enabling stacktrace filter. But with enabling STACK_UNWIND I feel big latency on X. (There are two type of implementation of stacktrace filter in it [1] using STACKTRACE with FRAME_POINTER, and [2] STACK_UNWIND) I don't know why there is quite difference between simple STACKTRACE and STACK_UNWIND. I'm about to try to use rb tree rather than linked list in unwind. In order to prevent from breaking other userspace programs and to inject failures into only a specific code or process, process filter and stacktrace filter are available. Without using them the system would be almost unusable. Now I'm stuck on the script in fault-injection.txt with random 700 modules. This script just tries to load/unload for all available kernel modules. It usually get several oopses or CPU soft lockup now. It seems that relatively large number of them involved around driver model (drivers/base/*). (I hope recent large number of error handle fixes especially by Jeff Garzik fix them) > Also, one place where this infrastructure could be of benefit is in device > drivers: simulate a bad sector on the disk, a pulled cable, a timeout > reading from a status register, etc. If that works well and is useful then > I can see us encouraging driver developers to wire up fault-injection in > the major drivers. > > Hence it would be useful at some stage to go in and to actually do all this > for a particular driver. As an example implementation for others to > emulate and as a test for the fault-injection infrastructure itself - we > may discover that new capabilities are needed as this work is done. > > I wouldn't say this is an urgent thing to be doing, but it is a logical > next step.. Yes. I'm learning from md/faulty and scsi-debug module what they are doing and how to integrate such kind of features in general form.