[rhelv6-list] Opinions on multi-head

[thomas at redhat.com]

On 06/04/2012 10:13 AM, Jussi Silvennoinen wrote:
>>> > > > As far as I know, ATI cards can only drive more than two
>>> displays if
>>> > > > you're using pure DisplayPort protocol. Using passive DP->DVI >
>>> > > adapters
>>> > > > you can only drive two monitors.
>>> > > > > ATI cards (in my case a 5770) are fine driving one monitor
>>> via an > > active
>>> > > DisplayPort->DVI adapter and two more by DVI directly for a total of
>>> > > three. It's the configuration I am running right now.
>>> > > I wound up going with the ATI FirePro v4900 for triple head on
>>> RHEL6.
>>> > I am using the DVI port, and two DisplayPort to DVI cables to drive
>>> > three monitors.
>>> > > An interesting note... The AMD binary driver locked up the machine.
>>> > Using the native RHEL driver, all three screens work, and I get
>>> > accelerated X and compiz works great.
>>>
>>> Out of curiosity, what kind of performance do you get? In something
>>> rudimentary like glxgears.
>>
>> Sorry for the delay in answering, I was travelling all week. It's not
>> spectacular, but certainly usable for my purposes. Like I said, I am
>> not a gamer, all I wanted was compiz to work on three heads. I just got:
>>
>> [tcameron at case ~]$ glxgears
>> Running synchronized to the vertical refresh. The framerate should be
>> approximately the same as the monitor refresh rate.
>> 298 frames in 5.0 seconds = 59.561 FPS
>> 300 frames in 5.0 seconds = 59.903 FPS
>
> Hum, how about 'export vblank_mode=0 ; glxgears'? Gaming aside, 2500fps
> from a Nvidia NVS290 wasn't enough to run compiz on a 3200x1200 dualhead
> smoothly enóugh for my taste. 9000fps from a Quadro 600 did the trick.
> Both using Nvidia's proprietary driver.

I'm running at 4320x900, or one desktop across three 1440x900 screens. 
Compiz works just fine to my eye.

To use the Quadro 600 for three monitors, I would have had to buy two of 
them, instead of the one V4900. Essentially that would double my cost, 
and add the hassle of proprietary drivers. Also, I MASSIVELY prefer to 
use OSS instead of closed source.

Anyway, I ran your command, and I got an average of about 4000fps. 
Plenty snappy for my use.

[tcameron at case Desktop]$ export vblank_mode=0 ; glxgears
ATTENTION: default value of option vblank_mode overridden by environment.
ATTENTION: default value of option vblank_mode overridden by environment.
17754 frames in 5.0 seconds = 3550.749 FPS
17699 frames in 5.0 seconds = 3539.472 FPS
20198 frames in 5.0 seconds = 4039.454 FPS
20367 frames in 5.0 seconds = 4073.230 FPS
20169 frames in 5.0 seconds = 4033.722 FPS
20567 frames in 5.0 seconds = 4112.590 FPS
20418 frames in 5.0 seconds = 4083.588 FPS
20467 frames in 5.0 seconds = 4093.272 FPS
20214 frames in 5.0 seconds = 4042.765 FPS
20504 frames in 5.0 seconds = 4100.681 FPS
20413 frames in 5.0 seconds = 4082.554 FPS
20481 frames in 5.0 seconds = 4096.033 FPS

TC
-- 
Thomas Cameron, RHCA, RHCSS, RHCDS, RHCVA, RHCX
Chief Architect, Canada and Central US
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