Re: [vserver] xorg inside of vguest slower than on host

From: Herbert Poetzl <herbert_at_13thfloor.at>
Date: Fri 07 Dec 2007 - 14:33:53 GMT
Message-ID: <20071207143353.GA18731@MAIL.13thfloor.at>

On Fri, Dec 07, 2007 at 08:17:06AM +0100, Stephan Mueller wrote:
> Hi,
>
> I managed to setup xorg 7.2 inside of a vguest by adding the device
> nodes tty7, mem and psaux as well as adding the SYS_RAWIO b-capability
> (fllowing the howto in the wiki).
>
> However, the xorg instance inside of the vguest seems to be much slower
> (when moving windows etc.) than one that is running on the host (same
> xorg release, both using debian lenny).
>
> I took a look at both resulting Xorg.logs and the only significant
> difference i can see is that the log from the host conatins lines as
> shown below whereas the vguests log does not have this kind of entries:
>
> (II) PCI: PCI scan (all values are in hex)
> (II) PCI: 00:00:0: chip 1002,7910 card 1458,5000 rev 00 class 06,00,00 hdr 00
> (II) PCI: 00:01:0: chip 1002,7912 card 0000,0000 rev 00 class 06,04,00 hdr 01
> (II) PCI: 00:12:0: chip 1002,4380 card 1458,b002 rev 00 class 01,06,01 hdr 00
> (II) PCI: 00:13:0: chip 1002,4387 card 1458,5004 rev 00 class 0c,03,10 hdr 80
> (II) PCI: 00:13:1: chip 1002,4388 card 1458,5004 rev 00 class 0c,03,10 hdr 00
> [...]
>
> This seems to result in the line
>
> (II) Setting vga for screen 0.
>
> which I can not find in the vguest log.
>
> For me this looks like the vguest does not have direct access to the
> graphics card.

could easily be ... Xorg does quite a number of low
level things (messing with the hardware)

> Any ideas if and how this could be improved?

you could, for a start, throw a bunch of capabilities
at the guest and disable (for testing) the proc hiding

> I would rather prefer running the xorg stuff inside of a vguest
> instead of on the host which is hosting several other vguests.

> A look at the lsof output for /dev did not reveal any other devices
> used by xorg on the host that are missing on the vguest.

it could get various device and control nodes/entries
from proc and/or sys .. check for those too (maybe
even strace a simple Xorg startup)

if you are interested in improving X (hardware access)
inside a guest, please let me know, if a number of folks
show interest and volunteer to test stuff, we could work
on improving X (hardware access) for certain guests

best,
Herbert

> Thanks and cheers,
>
> Steph.
Received on Fri Dec 7 14:34:08 2007

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