Complementing yesterday's Are The Open-Source Graphics Drivers Good Enough For Steam Linux Gaming? article is a look at the Steam Linux gaming performance for three different Intel Linux systems running Ubuntu 15.10 and firing up the latest Steam client. This is the last of the planned series that began one week ago with the a 22-way comparison of NVIDIA/AMD GPUs on SteamOS.
While three different Intel systems were tested for this article, it's not nearly as interesting as the proprietary driver SteamOS/Linux tests of the past few days. While yesterday's article with RadeonSI and Nouveau NVC0 supported hardware had some modern, interesting games, the Intel Linux driver doesn't run as many of them. Besides the Intel graphics processors being less powerful, their OpenGL driver still only officially has OpenGL 3.3 compliance.
Blocking the open-source Intel driver from having OpenGL 4.0 support is ARB_gpu_shader_fp64 and ARB_tessellation_shader support. Intel also has ARB_vertex_attrib_64bit missing for OpenGL 4.1 compliance while the changes for OpenGL 4.2 have already been cleared out. It still will probably be a bit of time before Intel is then up to OpenGL 4.2 compliance, but maybe we'll see it just in time for the next Mesa release.
Anyhow, with many Linux games these days targeting OpenGL 4.1~4.3, that means many of the notable Linux game ports on Steam cannot run out-of-the-box, like the Metro Redux titles, DiRT Showdown, Shadow of Mordor, Alien: Isolation, etc.
So for this testing, the limited games that do work on the Intel Linux driver at sufficient speed and the sub-set of them that then offer automated testing abilities that fit my needs for running the Phoronix Test Suite, it basically leaves Valve's Source Engine titles. The two games used for this comparison were Team Fortress 2 and Insurgency.
The processors used for testing was the Core i7 5775C Broadwell CPU with Iris Pro Graphics and then the Core i5 6500 and Core i5 6600K Skylake processors with HD Graphics 530. Ubuntu 15.10 64-bit was running on the system while for the latest open-source Intel Linux graphics experience upgrades were done to Linux 4.3 Git and Mesa 11.1-devel via the Padoka PPA.