From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 54058CF6D3B for ; Wed, 2 Oct 2024 16:58:14 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id D5F9A10E172; Wed, 2 Oct 2024 16:58:13 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="J9HQR38S"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) by gabe.freedesktop.org (Postfix) with ESMTPS id C091910E172; Wed, 2 Oct 2024 16:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1727888293; x=1759424293; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=dYIcv8D0ViAouND/v5b9Q3mTlvcQGTDBp2TYzg02xao=; b=J9HQR38Spw7ainDhh/WBP3fTfH5iJW4WbPxPZjr7TvnN5wZN6pEjJZ6B 16VxRQQW2oQmIn+FLU22bRfG9o9BVmngmylcBWkBRjY+GsrkAq0RKaFBZ M4YN+yFTPOXB+KgNDmyfzujpHAv9Ec2OBntLbfifm9QFD2GcUFDh+WYGp Q7RoL6JDHwP7feQ9EW117/meW2hKWdIU17dGIjHrmxWb9VI+YSMx+mtI/ gvA7Zax/F1HqyMhhEg/y0xb27jOYbeb9jE3/aRUZGRzJzAjI2qHkxWREz Vhgaaec1Pja4zQmBgWiXjIXVhl7bTnW4TP1S2zm9243MdPGlYJ0jFfA71 A==; X-CSE-ConnectionGUID: U1/vqqbTTBiA4NFpOu+6eQ== X-CSE-MsgGUID: vzUWXQQtQCWLDt7pCWEJXQ== X-IronPort-AV: E=McAfee;i="6700,10204,11213"; a="27155352" X-IronPort-AV: E=Sophos;i="6.11,172,1725346800"; d="scan'208";a="27155352" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Oct 2024 09:58:13 -0700 X-CSE-ConnectionGUID: n6DqjQbRQrCJkifr7Fu0xA== X-CSE-MsgGUID: xzgoS74dTfakdJJOpmrWAw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.11,172,1725346800"; d="scan'208";a="74181561" Received: from stinkpipe.fi.intel.com (HELO stinkbox) ([10.237.72.74]) by fmviesa008.fm.intel.com with SMTP; 02 Oct 2024 09:58:08 -0700 Received: by stinkbox (sSMTP sendmail emulation); Wed, 02 Oct 2024 19:58:08 +0300 Date: Wed, 2 Oct 2024 19:58:08 +0300 From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= To: Sebastian Andrzej Siewior Cc: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Thomas Gleixner , Tvrtko Ursulin Subject: Re: [PATCH v3 0/8] drm/i915: PREEMPT_RT related fixups. Message-ID: References: <20240628130601.1772849-1-bigeasy@linutronix.de> <20241002162543.TKbd-8g0@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241002162543.TKbd-8g0@linutronix.de> X-Patchwork-Hint: comment X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Wed, Oct 02, 2024 at 06:25:43PM +0200, Sebastian Andrzej Siewior wrote: > On 2024-06-28 14:57:59 [+0200], To intel-gfx@lists.freedesktop.org wrote: > Hi, > > > The following patches are from the PREEMPT_RT queue. It is mostly about > > disabling interrupts/preemption which leads to problems. Unfortunately > > DRM_I915_LOW_LEVEL_TRACEPOINTS had to be disabled because it acquires locks > > from within trace points. Making the lock a raw_spinlock_t led to higher > > latencies during video playback > > https://lore.kernel.org/all/20211006164628.s2mtsdd2jdbfyf7g@linutronix.de/ > > > > and I'm not sure if I hit the worse case here. > > I tested it on a SandyBridge with built-in i915 by using X, OpenGL and > > playing videos without noticing any warnings. However, some code paths > > were not entered. > > I carry them for some time now and most issues were reported by other > > people and they reported that things work for them since. > > These patches were not picked. Did I forget something or was this just > overseen? This looks quite poorly justified. Eg. you seem to be now leaving interrupts enabled (and even preemption enabled I guess) when we're racing against the raster beam. On first blush that seems like a recipe for failure. First step would be to set CONFIG_DRM_I915_DEBUG_VBLANK_EVADE=y, run a bunch of tests that stress the display stuff (eg. kms_atomic_transitions and other stuff from igt, and also some real workloads) and probably throw in a bunch of other load/perturbance at the system to make life hard. After the system has been sufficiently hammered one can compare sys/kernel/debug/dri/0/crtc-*/i915_update_info against a baseline. Bonus points for doing it on a potato. -- Ville Syrjälä Intel