From mboxrd@z Thu Jan  1 00:00:00 1970
From: Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [Intel-gfx] [PATCH v9 5/7] vfio: Define vfio based dma-buf
 operations
Date: Fri, 23 Jun 2017 10:31:28 +0200
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To: Zhi Wang <zhi.a.wang@intel.com>, Alex Williamson <alex.williamson@redhat.com>
Cc: "Wang, Zhenyu Z" <zhenyu.z.wang@intel.com>, "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "Chen, Xiaoguang" <xiaoguang.chen@intel.com>, "Zhang, Tina" <tina.zhang@intel.com>, Kirti Wankhede <kwankhede@nvidia.com>, "Lv, Zhiyuan" <zhiyuan.lv@intel.com>, "intel-gvt-dev@lists.freedesktop.org" <intel-gvt-dev@lists.freedesktop.org>
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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