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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB241C433F5 for ; Fri, 1 Oct 2021 10:37:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CC9561A7F for ; Fri, 1 Oct 2021 10:37:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352859AbhJAKj0 (ORCPT ); Fri, 1 Oct 2021 06:39:26 -0400 Received: from mga17.intel.com ([192.55.52.151]:21632 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231316AbhJAKjZ (ORCPT ); Fri, 1 Oct 2021 06:39:25 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10123"; a="205551056" X-IronPort-AV: E=Sophos;i="5.85,337,1624345200"; d="scan'208";a="205551056" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2021 03:37:41 -0700 X-IronPort-AV: E=Sophos;i="5.85,337,1624345200"; d="scan'208";a="619007698" Received: from howells-mobl.ger.corp.intel.com (HELO [10.213.208.92]) ([10.213.208.92]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Oct 2021 03:37:40 -0700 Subject: Re: [PATCH 17/28] drm/i915: use the new iterator in i915_gem_busy_ioctl v2 To: =?UTF-8?Q?Christian_K=c3=b6nig?= , linaro-mm-sig@lists.linaro.org, dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org, intel-gfx@lists.freedesktop.org Cc: daniel@ffwll.ch References: <20211001100610.2899-1-christian.koenig@amd.com> <20211001100610.2899-18-christian.koenig@amd.com> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc Message-ID: Date: Fri, 1 Oct 2021 11:37:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211001100610.2899-18-christian.koenig@amd.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 01/10/2021 11:05, Christian König wrote: > This makes the function much simpler since the complex > retry logic is now handled else where. > > Signed-off-by: Christian König > Reviewed-by: Tvrtko Ursulin Sorry I retract until you add the text about the increased cost of the added atomics. I think the point is important to discuss given proposal goes from zero atomics to num_fences * 2 (fence get/put unless I am mistaken) atomics per busy ioctl. That makes me lean towards just leaving this as is since it is not that complex. Regards, Tvrtko > --- > drivers/gpu/drm/i915/gem/i915_gem_busy.c | 35 ++++++++++-------------- > 1 file changed, 14 insertions(+), 21 deletions(-) > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_busy.c b/drivers/gpu/drm/i915/gem/i915_gem_busy.c > index 6234e17259c1..dc72b36dae54 100644 > --- a/drivers/gpu/drm/i915/gem/i915_gem_busy.c > +++ b/drivers/gpu/drm/i915/gem/i915_gem_busy.c > @@ -82,8 +82,8 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data, > { > struct drm_i915_gem_busy *args = data; > struct drm_i915_gem_object *obj; > - struct dma_resv_list *list; > - unsigned int seq; > + struct dma_resv_iter cursor; > + struct dma_fence *fence; > int err; > > err = -ENOENT; > @@ -109,27 +109,20 @@ i915_gem_busy_ioctl(struct drm_device *dev, void *data, > * to report the overall busyness. This is what the wait-ioctl does. > * > */ > -retry: > - seq = raw_read_seqcount(&obj->base.resv->seq); > - > - /* Translate the exclusive fence to the READ *and* WRITE engine */ > - args->busy = busy_check_writer(dma_resv_excl_fence(obj->base.resv)); > - > - /* Translate shared fences to READ set of engines */ > - list = dma_resv_shared_list(obj->base.resv); > - if (list) { > - unsigned int shared_count = list->shared_count, i; > - > - for (i = 0; i < shared_count; ++i) { > - struct dma_fence *fence = > - rcu_dereference(list->shared[i]); > - > + args->busy = 0; > + dma_resv_iter_begin(&cursor, obj->base.resv, true); > + dma_resv_for_each_fence_unlocked(&cursor, fence) { > + if (dma_resv_iter_is_restarted(&cursor)) > + args->busy = 0; > + > + if (dma_resv_iter_is_exclusive(&cursor)) > + /* Translate the exclusive fence to the READ *and* WRITE engine */ > + args->busy |= busy_check_writer(fence); > + else > + /* Translate shared fences to READ set of engines */ > args->busy |= busy_check_reader(fence); > - } > } > - > - if (args->busy && read_seqcount_retry(&obj->base.resv->seq, seq)) > - goto retry; > + dma_resv_iter_end(&cursor); > > err = 0; > out: >