I do agree though, they obviously fixed something that was horribly busted. If they can improve Linux video drivers more (performance and stability) I'm all for that. On my particular hardware anyway, caught between a rock and a hard place.. slower open drivers, or buggy but faster closed drivers. He also says he's going to see if he can apply that same adjustment to DirectX as well.. so right now its apparently a bit one sided.
That's the point, and that's why going all defensive about the FPS numbers posted on the Valve blog article is an exercise of butthurtness.
This is what they said, exactly:
After this work, Left 4 Dead 2 is running at 315 FPS on Linux. That the Linux version runs faster than the Windows version (270.6) seems a little counter-intuitive, given the greater amount of time we have spent on the Windows version. However, it does speak to the underlying efficiency of the kernel and OpenGL. Interestingly, in the process of working with hardware vendors we also sped up the OpenGL implementation on Windows. Left 4 Dead 2 is now running at 303.4 FPS with that configuration.
So what does this mean?
1.- Working with GPU vendors was great, since they achieved going from 6 to 315 FPS.
2.- The Linux kernel and OpenGL work great, since they managed to get great performance with less effort than they spent on the Windows version.
3.- While working on the Linux port they learned some tricks that also helped to improve Windows performance with OpenGL.
4.- They also found out that there was something going wrong with DirectX, so they can now try to fix that and improve the performance there as well.
If anyone feels like drawing other conclusions from that article and starting a platform war that's his problem. I'm not seeing anything other than an update of the work-in-progress of their port of L4D2 to Linux.