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Hardware Based XRender Slower than Software Rendering?
Neon Spiral Injector writes "Rasterman of Enlightenment fame has finally updated the news page of his personal site. It seems that the behind the scenes work for E is coming along. He is investigating rendering backends for Evas. The default backend is a software renderer written by Raster. Trying to gain a little more speed he ported it to the XRender extension, only to find that it became 20-50 times slower on his NVidia card. He has placed some sample code on this same news page for people to try, and see if this is also experienced on other setups."
I have used both ATI and NVIDIA,(and 3dfx, and matrox, but staying relevant). Generally the NVIDIA cards I have owned have been vastly outperformed by the ATI cards right off the bat, without tweakage. (This is under Linux, mind you) Even with tweakage, in my experience, you rarely get the full potential from your card.
I hate sigs.
Irix.
IrisGL or OpenGL (I think OpenGL is based on IrisGL, so Irix probably now uses OpenGL) is used extensively in Irix, for both 2D and 3D.
A solution to the problem with music today
Here is the entry from the driver README:
Following that option, this one is noted:
Normally, he would answer some questions or comments posted about something he has written, but he will be out of town for at least a few days.
I highly doubt he meant for this to get wide-spread exposure beyond developers of Enlightenment or X. Since it has, this is a good opportunity. I'll make this clear for anyone that didn't catch it, raster WANTS XRENDER TO BE FASTER! If there is a way to alter configuration or to recode the benchmark to do so, he wants to know about it.
Rather than posting questions about his configuration (which he can't answer right now), grab the benchmarks that he put up and get better results.
Now back to your regularly scheduled trolling...
Yes, and yes. :-)
The current version of Evas is actually the second iteration. The first version had a backend written for OpenGL, which performed quite well for large drawing areas, but was sluggish with many small areas (bad for window managers). The software engine easily outperformed in those cases, and will be used for the resulting window manager's border drawing.
For now, there is not an OpenGL engine in Evas, because of time constraints. E has a relatively small active development team atm, so it's difficult to say when someone will get around to adding the OpenGL engine. There should be one eventually, all nicely encapsulated except for a couple setup functions.
> There has been some work on using graphics cards for computation. The tough part is figuring out how to rephrase your algorithm in terms of what the GPU can handle.
Isn't there a lot of sloth involved in reading your results back as well?
Meanwhile, users of GCC can exploit whatever multimedia SIMD instructions their processor supports by telling the processor you want to use them. For x86 see this and this; for other architectures start here. (Notice the GCC version in the URL; the supported options sometimes change between versions, so you should look in a version of the GCC Manual that matches what you're actually using.)
I confess I haven't benchmarked these options, but in theory they should boost the performance of some kinds of number-crunching algorithms.
BTW, Linuxers can find what multimedia extensions their CPU supports with cat
And post us back if you do some benchmarking, or find some good ones on the Web.
Sheesh, evil *and* a jerk. -- Jade
If Tyranny and Oppression come to this land,
it will be in the guise of fighting a foreign enemy. -James Madison
On using OpenGL in multiple windows....
While my graphics hardware is not quite representative (the Matrox G450 is not known for great 3D performance), I ran two instances of glxgears.
Short conclusion: MesaGL on Linux has the same problem. Long conclusion: the windows showed noticable slowdowns, up to the point where animation was suspended in one window while the other ran, with the system switching the running window at seemingly random intervals.
System specs:
Hope this helps,
Mart
"I know I will be modded down for this": where's the option '-1, Asking for it'?
Obviously XRender is getting crushed here by Imlib2. There are a million reasons this might be happening, it's definitely worth looking into. In the best Slashdot tradition, here's some wild speculation about what might be causing the slowdown:
- Renderman's code might be giving an unfair advantage to Imlib2. The Imlib2 results are never shown on the screen. However, XRender is tested both with display and without, so it seems like it should be fair.
- Renderman's code might be using XRender in an inefficient way. I'm no X programming expert so I have no idea if what he's doing is the best way to do it, but Rasterman is supposed to be some sort of expert in producing nice fast graphics on X so I'd say this is unlikely.
- XRender might not be hardware accelerated for some reason, probably having to do with driver configuration or something. But geez, does the software rendering have to be that slow? Maybe they could learn something from Imlib2.
- The hotly debated "X protocol overhead" might be causing this slowdown. But given the magnitude of the slowdown, I think this is unlikely.
Hopefully someone knowledgeable like Keith Packard himself will come and enlighten us with the true cause.main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}
Must be your hardware. I have an Ath 2700 XP with a ATI 9800 running Debian with X 4.3
Single glxgears: 3600
3 glxgears: 1200
5 glxgears: 700
(All aprox numbers). So basically it scales almost perfectly with the number of open windows.
And the results were pretty much the same. Using render was several magnitudes slower on tests 2 - 7. I have a GeForce1 with 1.0.4349 nvidia driver and haven't had the same trouble others have with this option on so I run with this extension on all the time.
t up...
Here are the results for the interested:
Available XRENDER filters:
nearest
bilinear
fast
good
best
Se
*** ROUND 1 ***
Test: Test Xrender doing non-scaled Over blends Time: 0.190 sec.
Test: Test Xrender (offscreen) doing non-scaled Over blends Time: 0.303 sec.
Test: Test Imlib2 doing non-scaled Over blends Time: 0.697 sec.
*** ROUND 2 ***
Test: Test Xrender doing 1/2 scaled Over blends Time: 10.347 sec.
Test: Test Xrender (offscreen) doing 1/2 scaled Over blends Time: 10.231 sec.
Test: Test Imlib2 doing 1/2 scaled Over blends Time: 0.315 sec.
*** ROUND 3 ***
Test: Test Xrender doing 2* smooth scaled Over blends Time: 207.028 sec.
Test: Test Xrender (offscreen) doing 2* smooth scaled Over blends Time: 205.275 sec.
Test: Test Imlib2 doing 2* smooth scaled Over blends Time: 5.695 sec.
*** ROUND 4 ***
Test: Test Xrender doing 2* nearest scaled Over blends Time: 164.460 sec.
Test: Test Xrender (offscreen) doing 2* nearest scaled Over blends Time: 166.281 sec.
Test: Test Imlib2 doing 2* nearest scaled Over blends Time: 4.119 sec.
*** ROUND 6 ***
Test: Test Xrender doing general nearest scaled Over blends Time: 313.187 sec.
Test: Test Xrender (offscreen) doing general nearest scaled Over blends Time: 310.261 sec.
Test: Test Imlib2 doing general nearest scaled Over blends Time: 11.444 sec.
*** ROUND 7 ***
Test: Test Xrender doing general smooth scaled Over blends Time: 477.511 sec.
Test: Test Xrender (offscreen) doing general smooth scaled Over blends Time: 474.695 sec.
Test: Test Imlib2 doing general smooth scaled Over blends Time: 17.290 sec.
(reformatted to get past the lameness filter)
This ends up being even more true if you do any sort of complex compositing (eg: alpha blending, hardware accelerated mpeg / video, openGL windows, etc, etc). Enlightenment uses alpha channels, it would be fater to composite in hardware than software. These sorts of operations are not accelerated at all on the 2d path, and have to be done in software.
Go check out Quartz Extreme at http://www.apple.com/macosx/jaguar/quartzextreme.h tml (excuse the space in html).
Having used Xfree86 and Quartz extreme on the same graphics hardware, I can tell you there's no comparison. Quartz is much faster and much more capable.
Apple's OSX does all rendering through Quartz, (as PDFs) which is accelerated by OpenGL, and called QuartzExtreme.
:-)
That's not accurate. Quartz is really made of two parts: Quartz 2D and the Quartz Compositor.
The Quartz Compositor is reponsible for compositing all the layers (desktop, windows, layers inside windows) on-screen. It offers Porter-Duff compositing, which was developped at Pixar more than 15 years ago. See this post from Mike Paquette for details. Mr Paquette is one of the main developpers of Quartz. Quartz Extreme is "simply" an OpenGL implementation of Porter-Duff compositing and modern graphic cards offer the primitives needed to do that very efficiently.
The Quartz 2D layer is what offers drawing primitives following the Postscript drawing model. The same drawing model is used with PDF (no surprise), Java2D and SVG (and Microsoft's GDI+ ?). This part is not HW accelerated. I am sure Apple is working on it, but it wouldn't surprise me if new HW will be required to make this possible. There is a strong incentive for card manufacturers to offer acceleration, since Longhorn is supposed to use GDI+ extensively. I doubt that such acceleration will fit in the traditionnal OpenGL/Direct3D rendering pipeline.
The Apple JVM team implemented HW accelerated Java2D drawing in their 1.3.1 JVM. Their 1.4 JVM doesn't offer it (1.4.1 was a massive rewrite for them, 1.3.1 was more of a quick port to OS-X using some of their "old" carbon code). There were quite a few problems when HW acceleration was used. I hope they can and will wait for a system-wide Quartz-2D HW acceleration, it seems ludicrous to have the JVM team spend resources on an effort that will be wasted once Quartz2D is accelerated.
See Apple Marketing page, another post from Mike Paquette, and the presentation from Apple at SIGgraph about Quartz Extreme and OpenGL.
If that post doesn't end-up rated +5 informative, I don't know what will !
Which means it's broken. All the windows should run at full speed until the graphics pipeline saturates.
There are several problems. First, make sure that you're not running with "wait for VBLANK" off. There's a stupid overclocker mania for running the graphics system faster than the display can refresh. This leads to high, meaningless frame rates, and to lower system performance because the useless redraws are using up all the CPU time.
Once you're past that, the issues are more fundamental.
The real problem is that OpenGL is double-buffered, but most windowing systems don't understand double-buffering or frame-synchronous drawing very well. Even OpenGL has no notion of time. But this could be fixed.
Usually, each app draws into the back buffer, then makes the OpenGL call to swap the buffers. This blocks the app (older NVidia drivers for Windows spin-locked, but I got them to fix that), but worse, it typically locks up the OpenGL subsystem until the frame ends and the buffer swap occurs. Implementations like that can only draw one window per frame time, obviously.
What ought to happen is that a request for a buffer swap should schedule a buffer swap for the next frame cycle, block the app, then let other apps get in their draw time. At the end of the frame, when everybody is done drawing, all windows get buffer swapped, and all the apps stuck in the OpenGL buffer swap call then unblock simultaneously. That way, multiple OpenGL apps running in different windows all run at full frame rate, until the scene complexity hits the limits of the graphics hardware.
Part of the problem is that X and OpenGL are such drastically different architectures that making them play well together is tough. X assumes a network-centric model; OpenGL assumes you're local. X expects a weak terminal; OpenGL needs good graphics acceleration. X is built around a windowing concept; OpenGL doesn't know about windows. X and OpenGL are defined by different organizations.
Microsoft is pulling this together in the Windows world, but it's all done with Microsoft APIs, and, recently, undocumented hardware that favors those APIs.