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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, HK_RANDOM_FROM,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED44CC3F2D1 for ; Fri, 28 Feb 2020 11:53:25 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id C8AFB246AC for ; Fri, 28 Feb 2020 11:53:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C8AFB246AC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7646C6F431; Fri, 28 Feb 2020 11:53:25 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id 86D296F431 for ; Fri, 28 Feb 2020 11:53:24 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Feb 2020 03:53:24 -0800 X-IronPort-AV: E=Sophos;i="5.70,495,1574150400"; d="scan'208";a="232221906" Received: from pmulhall-mobl.ger.corp.intel.com (HELO [10.251.85.135]) ([10.251.85.135]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-SHA; 28 Feb 2020 03:53:23 -0800 To: Chris Wilson , intel-gfx@lists.freedesktop.org References: <20200227085723.1961649-1-chris@chris-wilson.co.uk> From: Tvrtko Ursulin Organization: Intel Corporation UK Plc Message-ID: Date: Fri, 28 Feb 2020 11:53:19 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200227085723.1961649-1-chris@chris-wilson.co.uk> Content-Language: en-US Subject: Re: [Intel-gfx] [PATCH 01/20] drm/i915: Skip barriers inside waits 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: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On 27/02/2020 08:57, Chris Wilson wrote: > Attaching to the i915_active barrier is a two stage process, and a flush > is only effective when the barrier is activation. Thus it is possible > for us to see a barrier, and attempt to flush, only for our flush to > have no effect. As such, before attempting to activate signaling on the > fence we need to double check it is a fence! > > Fixes: d13a31770077 ("drm/i915: Flush idle barriers when waiting") > Signed-off-by: Chris Wilson > Cc: Tvrtko Ursulin > --- > drivers/gpu/drm/i915/i915_active.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/gpu/drm/i915/i915_active.c b/drivers/gpu/drm/i915/i915_active.c > index 0b12d5023800..7b3d6c12ad61 100644 > --- a/drivers/gpu/drm/i915/i915_active.c > +++ b/drivers/gpu/drm/i915/i915_active.c > @@ -453,6 +453,9 @@ static void enable_signaling(struct i915_active_fence *active) > { > struct dma_fence *fence; > > + if (unlikely(is_barrier(active))) > + return; > + > fence = i915_active_fence_get(active); > if (!fence) > return; > So that smp_rmb() is not really effective, I mean the race is wider than that. I was worried about that.. now I need to figure out where it starts and where it ends (the race). Regards, Tvrtko _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx