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 423F0C433F5 for ; Mon, 21 Mar 2022 11:04:05 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 9391F10E319; Mon, 21 Mar 2022 11:04:04 +0000 (UTC) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 2990810E319; Mon, 21 Mar 2022 11:04:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1647860643; x=1679396643; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=ee9LFigG3BJzoa27u8jzD9bFriJepHX9vTAeMbhx2NU=; b=iNks5cOs90ECAkQYC8qZdCixK9D9IBrLFAjpmOUHGwQmTbNaaqkreMUC rifydvNmeLNQGzluvpKJhB6ZmEU41bUAiW3cAoetun2dQs8NEVN/SkQzo UmgFHAE8PtYlwHtlA+c5ALpLmFprAxNcGBJxdfS5qR3mzbPFVLpNvRxDX nothxpxXha9ODHeQN82pn0Gr3thctKmeKnzXjtG+bsrQvV/BYL47ipcrm i3lVuInXOzL3/RZJhRPFCiKkFzOukbnpUM6Pkb4FnyXdj9CVUTtbg70Nz K/osVHPpVBH3bAPm02wP5whsGzpJI/PNJV1j5vrcpw8QDzFip2NNvSTOk w==; X-IronPort-AV: E=McAfee;i="6200,9189,10292"; a="318234082" X-IronPort-AV: E=Sophos;i="5.90,198,1643702400"; d="scan'208";a="318234082" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Mar 2022 04:04:02 -0700 X-IronPort-AV: E=Sophos;i="5.90,198,1643702400"; d="scan'208";a="824354872" Received: from evinintel.ger.corp.intel.com (HELO [10.249.254.209]) ([10.249.254.209]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Mar 2022 04:03:59 -0700 Message-ID: <5db61477-6064-ada0-82a7-c1dc659dacad@linux.intel.com> Date: Mon, 21 Mar 2022 12:03:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Content-Language: en-US To: Tvrtko Ursulin , Michael Cheng , intel-gfx@lists.freedesktop.org References: <20220319194227.297639-1-michael.cheng@intel.com> <4c86ae70-6f97-7a7c-1fd4-5e73ca29d0ba@linux.intel.com> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= In-Reply-To: <4c86ae70-6f97-7a7c-1fd4-5e73ca29d0ba@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: Re: [Intel-gfx] [PATCH 0/4] Drop wbinvd_on_all_cpus usage 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: , Cc: daniel.vetter@ffwll.ch, lucas.demarchi@intel.com, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, Matthew Auld Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Hi, Tvrtko. On 3/21/22 11:27, Tvrtko Ursulin wrote: > > On 19/03/2022 19:42, Michael Cheng wrote: >> To align with the discussion in [1][2], this patch series drops all >> usage of >> wbvind_on_all_cpus within i915 by either replacing the call with certain >> drm clflush helpers, or reverting to a previous logic. > > AFAIU, complaint from [1] was that it is wrong to provide non x86 > implementations under the wbinvd_on_all_cpus name. Instead an arch > agnostic helper which achieves the same effect could be created. Does > Arm have such concept? I also understand Linus' email like we shouldn't leak incoherent IO to other architectures, meaning any remaining wbinvd()s should be X86 only. Also, wbinvd_on_all_cpus() can become very costly, hence prefer the range apis when possible if they can be verified not to degrade performance. > > Given that the series seems to be taking a different route, avoiding > the need to call wbinvd_on_all_cpus rather than what [1] suggests > (note drm_clflush_sg can still call it!?), concern is that the series > has a bunch of reverts and each one needs to be analyzed. Agreed. /Thomas > > For instance looking at just the last one, 64b95df91f44, who has > looked at the locking consequences that commit describes: > > """ >     Inside gtt_restore_mappings() we currently take the > obj->resv->lock, but >     in the future we need to avoid taking this fs-reclaim tainted lock > as we >     need to extend the coverage of the vm->mutex. Take advantage of the >     single-threaded nature of the early resume phase, and do a single >     wbinvd() to flush all the GTT objects en masse. > > """ > > ? > > Then there are suspend and freeze reverts which presumably can regress > the suspend times. Any data on those? > > Adding Matt since he was the reviewer for that work so might remember > something. > > Regards, > > Tvrtko > > >> [1]. >> https://lists.freedesktop.org/archives/dri-devel/2021-November/330928.html >> [2]. https://patchwork.freedesktop.org/patch/475752/?series=99991&rev=5 >> >> Michael Cheng (4): >>    i915/gem: drop wbinvd_on_all_cpus usage >>    Revert "drm/i915/gem: Almagamate clflushes on suspend" >>    i915/gem: Revert i915_gem_freeze to previous logic >>    drm/i915/gt: Revert ggtt_resume to previous logic >> >>   drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c |  9 +--- >>   drivers/gpu/drm/i915/gem/i915_gem_pm.c     | 56 ++++++++++++++-------- >>   drivers/gpu/drm/i915/gt/intel_ggtt.c       | 17 +++---- >>   drivers/gpu/drm/i915/gt/intel_gtt.h        |  2 +- >>   4 files changed, 46 insertions(+), 38 deletions(-) >>