linux-kernel - RE: [PATCH v5 0/6] Deliver vGPU display refresh event to userspace

Open Source and information security mailing list archives

Message-ID: <237F54289DF84E4997F34151298ABEBC87734BB6@SHSMSX101.ccr.corp.intel.com>
Date:   Tue, 17 Sep 2019 09:27:08 +0000
From:   "Zhang, Tina" <tina.zhang@...el.com>
To:     "kraxel@...hat.com" <kraxel@...hat.com>,
        "Tian, Kevin" <kevin.tian@...el.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Yuan, Hang" <hang.yuan@...el.com>,
        "alex.williamson@...hat.com" <alex.williamson@...hat.com>,
        "Lv, Zhiyuan" <zhiyuan.lv@...el.com>,
        "intel-gvt-dev@...ts.freedesktop.org" 
        <intel-gvt-dev@...ts.freedesktop.org>
Subject: RE: [PATCH v5 0/6] Deliver vGPU display refresh event to userspace

> -----Original Message-----
> From: intel-gvt-dev [mailto:intel-gvt-dev-bounces@...ts.freedesktop.org] On
> Behalf Of kraxel@...hat.com
> Sent: Thursday, September 5, 2019 3:49 PM
> To: Zhang, Tina <tina.zhang@...el.com>
> Cc: kvm@...r.kernel.org; linux-kernel@...r.kernel.org; Yuan, Hang
> <hang.yuan@...el.com>; alex.williamson@...hat.com; Lv, Zhiyuan
> <zhiyuan.lv@...el.com>; intel-gvt-dev@...ts.freedesktop.org
> Subject: Re: [PATCH v5 0/6] Deliver vGPU display refresh event to userspace
> 
>   Hi,
> 
> > Option 2: QEMU provides the emulated display refresh event to the
> > vgpus provided by vendor driver. For vgpus, the display refresh event
> > can be considered as the vblank event which is leveraged by guest
> > window manager to do the plane update or mode-setting.
> 
> > People are asking if option 2 could be a better choice.
> 
> Certainly worth trying, maybe it even makes sense to implement both and
> let qemu pick one, possibly even switch them at runtime.
> 
> qemu can change the refresh rate.  vnc and sdl use that to reduce the
> refresh rate in case nobody is looking (no vnc client connected, sdl window
> minimized).  It surely makes sense to make that visible to the guest so it can
> throttle display updates too.  I'm not sure vblank is the way to go though,
> guests might run into vblank irq timeouts in case the refresh rate is very
> low ...

Indeed, low vblank rate isn't expected by guest gfx driver. It complains about the timeout error all the time, when the vblank is low. 

Currently, gvt-g provides full virtualized display model (a.k.a. not pv). And the option 2 is more like a pv solution for performance optimization, which is of course a very good proposal. Since the two options have no dependency, this patch-set limits its scope to only include option 1. Thanks.

BR,
Tina

> 
> cheers,
>   Gerd
> 
> _______________________________________________
> intel-gvt-dev mailing list
> intel-gvt-dev@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gvt-dev

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives