AMD's Open-Source Radeon Driver After Four Years
Linked by David Adams on Thu 18th Aug 2011 19:09 UTC, submitted by Michael
Graphics, User Interfaces While the BFS scheduler is getting ready to celebrate its second birthday, in just three weeks AMD's open-source Radeon graphics driver strategy for Linux will be turning four years old . . . which has ended up being a game-changer in the Linux world. AMD continues to support open-source hardware enablement on their latest graphics processors and recently even hired more developers to work on the code and documentation. How far have they come though in four years?
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lemur2
Member since:
2007-02-17

I'm not sure why you believe that the open source driver will overtake the closed-source one in a few months time. It's really hard work to get that performance out, and I really doubt the Linux driver team has the same resources as the Windows driver team at AMD. Btw, it's not 80% now on new cards, it's still closer to 50-60% I think. The 80% figure is relevant for cards that are about 6-7 years old, as far as I can tell.


The programming specification documents that AMD/ATI released are here:

http://www.x.org/docs/AMD/

Note the dates. The documents for the older cards were released (~ early 2008) about a year before the documents for the newer cards (~ early 2009). There is a direct correspondence to the performance, in that there is better performance (relative to closed source driver for the same card) for those older cards where the open source developers have had a year longer to work on the drivers.

That is the first point. Given the same amount of time, it would be reasonable to expect a similar improvement for newer cards as we see now for the older cards. In fact, having gone through the process once for the older cards, the still-to-be-done performance fine tuning for the newer cards might even happen quicker.

The second point is that closed source drivers are developed for Windows. The majority of this code is then re-used for Linux, with a small open source wrapper program to interface to the different kernel. The drivers are optimised for Windows. Because of that fact, and also the fact that the closed source drivers require an extra "adapter" layer, it is reasonable to expect that eventually the open source drivers will catch up, given that they are tuned for Linux.

Apart from the development going on at Xorg, AMD itself has been hiring new open source developers of late.

Edited 2011-08-19 04:59 UTC

Reply Parent Score: 2

saynte Member since:
2007-12-10

That's precisely my point: the older cards are now at about 80% on average. So if we apply your reasoning, then a year from now we will have the same 80% performance of the newer cards, which I wouldn't say is really "overtaking" the closed source drivers.

In terms of the drivers being written for Windows vs Linux, I think there's not much of an overhead from the current Catalyst drivers being first developed for Windows.

For example:

http://www.phoronix.com/scan.php?page=article&item=897&num=1

Reply Parent Score: 1

lemur2 Member since:
2007-02-17

That's precisely my point: the older cards are now at about 80% on average. So if we apply your reasoning, then a year from now we will have the same 80% performance of the newer cards, which I wouldn't say is really "overtaking" the closed source drivers. In terms of the drivers being written for Windows vs Linux, I think there's not much of an overhead from the current Catalyst drivers being first developed for Windows. For example: http://www.phoronix.com/scan.php?page=article&item=897&num=1


In terms of pure raw performance, it is probable that open source drivers will only ever catch up to closed source drivers.

In terms of overall working, even at 80% raw performance (speed), the open source drivers are already ahead of the proprieatry graphics drivers for Linux. The open source drivers will work "out of the box", whereas the closed source drivers are simply not supported any longer. If you have an older ATI card on your Linux box, already it would be utter insanity for you to run anything other than the open source radeon driver written at Xorg.

There are some games for Linux now which work better under the open source drivers than they do under the closed source drivers. World of Padman is one.

http://www.phoronix.com/scan.php?page=article&item=amd_four_r300&nu...

World of Padman, which is powered by the ioquake3 engine like OpenArena, shed a slightly different story. The R400-based Radeon X800XL was now at 78% the speed of Catalyst and the R500-based Radeon X1800XT was actually faster on the open-source driver. The Radeon X1800XT was straight-up 25% faster on the latest open-source Linux driver code than the Catalyst driver right before its R500 series support was dropped. The rendering for both drivers in this game was also correct.


In other cases it is, of course, the other way around, as shown for OpenArena on that same page.

Being open source, this allows people to investigate exactly why World of Padman is faster than OpenArena. This in turn allows two things to happen:

(1) driver developers can focus their efforts to improve performance by seeing where OpenArena performance is low, and
(2) game developers can use the better performance in areas where World of Padman is strong as the basis of their game engines.

Just by natural evolution the performance of games on Linux will eventually be better with the open source drivers than with closed source drivers. It is inevitable.

Edited 2011-08-19 06:12 UTC

Reply Parent Score: 2

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