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=-3.8 required=3.0 tests=BAYES_00, 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 89A36C433B4 for ; Fri, 30 Apr 2021 23:00:56 +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 1AC32613B1 for ; Fri, 30 Apr 2021 23:00:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1AC32613B1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 00C4C6F60B; Fri, 30 Apr 2021 23:00:55 +0000 (UTC) Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id E2DB16F60B; Fri, 30 Apr 2021 23:00:53 +0000 (UTC) IronPort-SDR: q0xaRtS6T+qlUnDojnibKCVPUIlIlBgwjgW+O5VIGoSwcGsaw+ds87xK1sVEen8hyhV1U8JqBV d6GKc/8If8Fg== X-IronPort-AV: E=McAfee;i="6200,9189,9970"; a="184518681" X-IronPort-AV: E=Sophos;i="5.82,264,1613462400"; d="scan'208";a="184518681" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2021 16:00:48 -0700 IronPort-SDR: 0HfX+cCXYNhbDiQzkiE9985D+RSLRRulyzUcoMnLpdCTuogEUV9LSPhA9YS3FiEzzC5taGuX97 yCTovORf09yg== X-IronPort-AV: E=Sophos;i="5.82,264,1613462400"; d="scan'208";a="459689361" Received: from adixit-mobl1.amr.corp.intel.com (HELO adixit-arch.intel.com) ([10.212.201.129]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Apr 2021 16:00:47 -0700 Date: Fri, 30 Apr 2021 16:00:46 -0700 Message-ID: <87czubbco1.wl-ashutosh.dixit@intel.com> From: "Dixit, Ashutosh" To: Umesh Nerlige Ramappa Subject: Re: [PATCH 1/1] i915/query: Correlate engine and cpu timestamps with better accuracy In-Reply-To: <20210430222609.GC38093@orsosgc001.ra.intel.com> References: <20210429003410.69754-1-umesh.nerlige.ramappa@intel.com> <20210429003410.69754-2-umesh.nerlige.ramappa@intel.com> <20210430222609.GC38093@orsosgc001.ra.intel.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?ISO-8859-4?Q?Goj=F2?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.2 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Intel GFX , Maling list - DRI developers , Jason Ekstrand Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Fri, 30 Apr 2021 15:26:09 -0700, Umesh Nerlige Ramappa wrote: > > Looks like the engine can be dropped since all timestamps are in sync. I > just have one more question here. The timestamp itself is 36 bits. Should > the uapi also report the timestamp width to the user OR should I just > return the lower 32 bits of the timestamp? How would exposing only the lower 32 bits of the timestamp work? The way to avoid exposing the width would be to expose the timestamp as a regular 64 bit value. In the kernel engine state, have a variable for the counter and keep on accumulating that (on each query) to full 64 bits in spite of the 36 bit HW counter overflow. So not exposing the width (or exposing a 64 bit timestamp) is a cleaner interface but also more work in the kernel. _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel