Comments on: A Tale of Three Operating Systems

By: Peter

Peter — Mon, 30 Oct 2006 07:12:00 +0000

I think it would be really interesting to see what the framerates would look like under Windows with ATItool set to the proper clock speed..
There is plenty of info on xlr8yourmac.com about how Apple underclocked the X1600 on the MacBookPro
I would be very interested to se the results, since I have the same machine.
Also, from what I understand, the fans go right to their 6000RPM limt in Windows, regardless of workload, this would provide ample cooling..

By: Anonymous

Anonymous — Sat, 07 Oct 2006 00:57:00 +0000

yah i think linux would have looked better with a nvidia gpu and also with a different distro. In my experience deb based ones are slower than slack ones. but ubuntu is the most popular so it makes sense to use it in the benchmarks. thanks for the test.

By: Benjamin Supnik

Benjamin Supnik — Fri, 06 Oct 2006 14:28:00 +0000

Yes -- I am not surprised on those numbers...what I found with VBOs was:

- In WorldMaker, there are misdrawn polygons and other weird visual artifacts with VBOs on in the terrain mesh.

- For terrrain-only rendering, VBOs slow me down...probably because the bogus vertices make huge triangles that use up pixel-fill.

- For tons of objects, the OBJs don't seem to be affected by the bug, so we benefit from having VBOs.

In particular, objects have their VBOs in VRAM when possible, so the performance difference for lots of OBJs with VBOs is quite large.

On my machine I get a segfault in Linux when using --fps_test=3 when the app exits.

By: Anonymous

Anonymous — Fri, 06 Oct 2006 14:12:00 +0000

I did a quick check on the influence of --no_vbus on Linux, which should give some sort of impression on how much performance this option costs:

fps-test 3 with vbus: 21/21/21
fps-test 3 without vbus: 10/10/11

By: Benjamin Supnik

Benjamin Supnik — Fri, 06 Oct 2006 09:05:00 +0000

I don’t think it’s fair to generalize nVidia’s drivers in with ATIs; all feedback we’ve gotten from our users is that nVidia’s proprietary drivers on Linux cause less problems than ATIs, and nVidia has told us that the proprietary part of the Linux driver _is_ the Windows driver – that is they host their Windows driver inside Linux. We’d have to see a framerate comparison on the same machine, dual-boot to know the true performance gap.

Sadly caching doesn’t contribute to real performance boosts in X-Plane with one possible exception – if you fly in circles around a set of DSFs and the circle is tight enough perhaps you could load the same files over and over again. But artwork is only loaded once and DSFs are not reloaded anymore during linear flight.

By: Bruce Cowan

Bruce Cowan — Fri, 06 Oct 2006 08:57:00 +0000

The slowness of Linux in FPS is probably due to the fact that the official drivers from ATI/nVidia aren't very good, and they lag behind the Windows drivers of the same version.

Linux was the fastest at reloading files as it caches almost everything into memory. (I have 525676k used memory, where 247892k of that is cached from the hard disk).

This is with Ubuntu 6.10.