Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754012AbdFWIbd (ORCPT ); Fri, 23 Jun 2017 04:31:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41936 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751217AbdFWIbb (ORCPT ); Fri, 23 Jun 2017 04:31:31 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 8BD4C368E5 Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=kraxel@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 8BD4C368E5 Message-ID: <1498206688.24807.5.camel@redhat.com> Subject: Re: [Intel-gfx] [PATCH v9 5/7] vfio: Define vfio based dma-buf operations From: Gerd Hoffmann To: Zhi Wang , Alex Williamson Cc: "Wang, Zhenyu Z" , "intel-gfx@lists.freedesktop.org" , "linux-kernel@vger.kernel.org" , "Chen, Xiaoguang" , "Zhang, Tina" , Kirti Wankhede , "Lv, Zhiyuan" , "intel-gvt-dev@lists.freedesktop.org" Date: Fri, 23 Jun 2017 10:31:28 +0200 In-Reply-To: <594CC7F6.7050507@intel.com> References: <1497513611-2814-1-git-send-email-xiaoguang.chen@intel.com> <1497513611-2814-6-git-send-email-xiaoguang.chen@intel.com> <1497542438.29252.1.camel@redhat.com> <20170615143833.7526351b@w520.home> <24c4880b-24f5-ea07-834c-c77d3e895c78@nvidia.com> <1497854312.4207.4.camel@redhat.com> <20170619085530.1f5e46dc@w520.home> <237F54289DF84E4997F34151298ABEBC7C56EBE0@SHSMSX101.ccr.corp.intel.com> <1497956256.16795.7.camel@redhat.com> <20170620090004.44ac7fbc@w520.home> <237F54289DF84E4997F34151298ABEBC7C56F3DC@SHSMSX101.ccr.corp.intel.com> <20170620172204.09405cf4@w520.home> <237F54289DF84E4997F34151298ABEBC7C56F843@SHSMSX101.ccr.corp.intel.com> <1498043011.5802.5.camel@redhat.com> <20170621125938.1a92abda@w520.home> <1498120215.25651.5.camel@redhat.com> <20170622125458.01c953ab@w520.home> <1498202819.24807.3.camel@redhat.com> <594CC7F6.7050507@intel.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Fri, 23 Jun 2017 08:31:30 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 727 Lines: 21 On Fri, 2017-06-23 at 15:49 +0800, Zhi Wang wrote: > Hi: >      Thanks for the discussions! If the userspace application has  > already maintained a LRU list, it looks like we don't need > generation  > anymore, generation isn't required, things are working just fine without that. It is just a small optimization, userspace can skip the LRU lookup altogether if the generation didn't change. But of couse that only pays off if the kernel doesn't has to put much effort into maintaining the generation id. Something simple like increasing it each time the guest writes a register which affects plane_info. If you think it doesn't make sense from the driver point of view we can drop the generation. cheers, Gerd