From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Widawsky Subject: Re: [PATCH 0/6] Page faults to help user space debug Date: Sat, 29 Jun 2013 14:20:40 -0700 Message-ID: <20130629212040.GA690@bwidawsk.net> References: <1372458217-2053-1-git-send-email-ben@bwidawsk.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from shiva.localdomain (unknown [209.20.75.48]) by gabe.freedesktop.org (Postfix) with ESMTP id 185B9E5CFD for ; Sat, 29 Jun 2013 14:17:29 -0700 (PDT) Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: Daniel Vetter Cc: Paul Berry , Intel GFX List-Id: intel-gfx@lists.freedesktop.org On Sat, Jun 29, 2013 at 04:38:00PM +0200, Daniel Vetter wrote: > On Sat, Jun 29, 2013 at 12:23 AM, Ben Widawsky wrote: > > 2. echo 2 > /sys/kernel/debug/dri/0/i915_debug_flags > > Unbind all buffers synchronously, so any batch which has bad code will fault > > every time and not get lucky by hitting a buffer it bound. This will not catch > > cases where it accidentally reads/writes someone else's buffer. > > We already have this as the drop_caches debugfs interface. Chris used > it to reproduce the 3.7 reloc-tree regression, the only downside is > that no one ever got around to write the respective i-g-t ... :( > -Daniel In order to achieve the same behavior, one must instrument every GPU client to use that interface before, and after every batch (you can skip one if you're positive all clients have opted in). Also, every client must be run as root. This mechanism I've introduced is much simpler to achieve the intended result. > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch -- Ben Widawsky, Intel Open Source Technology Center