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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 B7221C38A2A for ; Fri, 8 May 2020 15:46:58 +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 924882173E for ; Fri, 8 May 2020 15:46:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 924882173E 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 377ED89BF3; Fri, 8 May 2020 15:46:58 +0000 (UTC) Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4B14989BF3 for ; Fri, 8 May 2020 15:46:57 +0000 (UTC) IronPort-SDR: 6fW/TPLYA0IKdk5dw6L2ktdoWRQrwK0HwGxgce3FD4iUBhVicrn2vByw28OpRjezQa/rmj1WQJ agVbUUohuUoA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 May 2020 08:46:56 -0700 IronPort-SDR: TE9uioLZoRaILEklJG0Dz3sz09sUMNB3JT8FtZzhRwEUmpvZwY9iz7XqLXhFLmdyYEwZxK76BS Um2WsOhi5P7Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,368,1583222400"; d="scan'208";a="285506553" Received: from gaia.fi.intel.com ([10.237.72.192]) by fmsmga004.fm.intel.com with ESMTP; 08 May 2020 08:46:56 -0700 Received: by gaia.fi.intel.com (Postfix, from userid 1000) id 0C8E75C1DC1; Fri, 8 May 2020 18:44:48 +0300 (EEST) From: Mika Kuoppala To: Chris Wilson , intel-gfx@lists.freedesktop.org In-Reply-To: <158895262946.30605.1038065551850826772@build.alporthouse.com> References: <20200508092933.738-1-chris@chris-wilson.co.uk> <20200508092933.738-3-chris@chris-wilson.co.uk> <87a72ixwt0.fsf@gaia.fi.intel.com> <158895262946.30605.1038065551850826772@build.alporthouse.com> Date: Fri, 08 May 2020 18:44:48 +0300 Message-ID: <87eeru4ej3.fsf@gaia.fi.intel.com> MIME-Version: 1.0 Subject: Re: [Intel-gfx] [PATCH 3/9] drm/i915: Prevent using semaphores to chain up to external fences 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" Chris Wilson writes: > Quoting Mika Kuoppala (2020-05-08 16:37:15) >> Chris Wilson writes: >> >> > The downside of using semaphores is that we lose metadata passing >> > along the signaling chain. This is particularly nasty when we >> > need to pass along a fatal error such as EFAULT or EDEADLK. For >> > fatal errors we want to scrub the request before it is executed, >> > which means that we cannot preload the request onto HW and have >> > it wait upon a semaphore. >> >> b is waiting on a, a fails and we want to release b with error? > > Yes. B is submitted before A, and if B is relying on A to setup GPU page I guess this has to be A is before B. > tables or other interesting things, we can't let B run if A dies. For > the EDEADLK if B is waiting on A, but then A is submitted with a wait on > B -- we have to untangle that mess. Avoiding the hw semaphore makes sense Reviewed-by: Mika Kuoppala > -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/intel-gfx