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<div>Hi Alain,</div>
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<div>Yes, "Gerd's" I meant of course, sorry. Thank you for the link!<br>
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<div>Best regards,</div>
Dmitry.<br>
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<div id="divRpF762550" style="direction: ltr;"><font size="2" face="Tahoma" color="#000000"><b>From:</b> Alain Magloire [amagloire@blackberry.com]<br>
<b>Sent:</b> Thursday, August 20, 2020 16:51<br>
<b>To:</b> Dmitry Sepp; Chia-I Wu; Vasyl Vavrychuk<br>
<b>Cc:</b> virglrenderer-devel<br>
<b>Subject:</b> Re: [virglrenderer-devel] virgl_renderer_resource_import_eglimage<br>
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<p>Bonjour,</p>
<p><br>
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<p>You mean Gerd... I think it is on his Kraxel news blog</p>
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<p><a href="https://www.kraxel.org/blog/2019/11/virtio-gpu-status-and-plans/" class="OWAAutoLink" target="_blank" rel="noopener noreferrer">https://www.kraxel.org/blog/2019/11/virtio-gpu-status-and-plans/</a></p>
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<div id="divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Dmitry Sepp <Dmitry.Sepp@opensynergy.com><br>
<b>Sent:</b> Thursday, August 20, 2020 5:09 AM<br>
<b>To:</b> Alain Magloire; Chia-I Wu; Vasyl Vavrychuk<br>
<b>Cc:</b> virglrenderer-devel<br>
<b>Subject:</b> RE: [virglrenderer-devel] virgl_renderer_resource_import_eglimage</font>
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<div>Hi Alain,</div>
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<div>Could you please point to some of the Greg's proposals?</div>
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<div>Thanks in advance.</div>
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<div>Best regards,<br>
Dmitry.<br>
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<div id="divRpF736864" style="direction:ltr"><font size="2" face="Tahoma" color="#000000"><b>From:</b> virglrenderer-devel [virglrenderer-devel-bounces@lists.freedesktop.org] on behalf of Alain Magloire [amagloire@blackberry.com]<br>
<b>Sent:</b> Thursday, August 20, 2020 01:18<br>
<b>To:</b> Chia-I Wu; Vasyl Vavrychuk<br>
<b>Cc:</b> virglrenderer-devel<br>
<b>Subject:</b> Re: [virglrenderer-devel] virgl_renderer_resource_import_eglimage<br>
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<p>Bonjour,</p>
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<p>Yes, it is my understanding that virtio-gpu allocates memory on the guest.</p>
<p>Then on the host you will have the corresponding backing store... <br>
</p>
<p>if synchronization is needed, then you will get a transfer Host to guest and vice-versa and your performance is.. not great.</p>
<p>The transfer to the attach backing is basically a memcpyv().<br>
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<p>On Android, it can get more challenging, as Android is not killing apps, but relying on the lmkd (low memory killer) to take actions...</p>
<p>Except that the graphics memory being consumed by guest... is actually on the host... sigh... the accounting is off.</p>
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<p>They are different possible strategies to deal with this.</p>
<p>Gerd H proposed a few...</p>
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<p>Thanks<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> virglrenderer-devel <virglrenderer-devel-bounces@lists.freedesktop.org> on behalf of Chia-I Wu <olvaffe@gmail.com><br>
<b>Sent:</b> Wednesday, August 19, 2020 6:40:38 PM<br>
<b>To:</b> Vasyl Vavrychuk<br>
<b>Cc:</b> virglrenderer-devel<br>
<b>Subject:</b> Re: [virglrenderer-devel] virgl_renderer_resource_import_eglimage</font>
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<div class="PlainText">On Wed, Aug 19, 2020 at 3:12 PM Vasyl Vavrychuk <vvavrychuk@gmail.com> wrote:<br>
><br>
> On Wed, Aug 19, 2020 at 10:02 PM Chia-I Wu <olvaffe@gmail.com> wrote:<br>
> ><br>
> > On Wed, Aug 19, 2020 at 1:42 AM Vasyl Vavrychuk <vvavrychuk@gmail.com> wrote:<br>
> > ><br>
> > > Commit message for commit that adds "virgl_renderer_resource_import_eglimage" says this function supposed to be used from CrosVM. But I have checked CrosVM source and did not find virgl_renderer_resource_import_eglimage usage. Same for QEMU.<br>
> > ><br>
> > > As I understand virgl_renderer_resource_import_eglimage is essential to achieve zero copy. So, why QEMU/CrosVM do not use it. Are they using some other methods to achieve zero copy?<br>
> ><br>
> > I think crosvm moved from import model to export model a while ago.<br>
> > It probably uses virgl_renderer_export_query now (didn't verify).<br>
><br>
> You are right, crosvm does export fd and then "RegisterFdAtPciBarOffset".<br>
><br>
> But, as far as I understand, this means that resources are allocated<br>
> from host memory. In embedded systems, usually video memory is the<br>
> same as RAM, but here RAM accessible to the guest and video memory<br>
> provided by virglrenderer/crosvm will be separate. So I will have to<br>
> limit separately, that for example, my guest should have 2 GB of RAM<br>
> and 1 GB of video memory. Kindly please confirm that my understanding<br>
> is correct.<br>
<br>
That is correct, but it has nothing to do with importing or exporting.<br>
The difference is whether crosvm or virglrenderer allocates, but those<br>
allocations are not from the guest memory no matter who allocates. I<br>
think at least virglrenderer does not put any limit.<br>
<br>
For qemu 2D mode, there is indeed a property called max_hostmem to<br>
limit total host allocation size.<br>
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