As mentioned back in March, Valve's encountered OpenGL Linux performance problems. Those problems haven't been for the open-source Mesa/Gallium3D drivers that are riddled with issues and incomplete functionality, but with the proprietary AMD and NVIDIA Linux drivers. I haven't checked recently but I hope those performance issues are now worked out with the latest upstream binary blobs. I would assume those OpenGL performance problems have been worked out with Valve Software showing their Linux client to partners. Aside from Linux OpenGL, Valve is now evidently uncovering non-graphics related problems.
Case in point is "[PATCH v2] perf symbols: Follow .gnu_debuglink section to find separate symbols." This recently-patched bug is addressing a Linux perf issue. "The .gnu_debuglink section is specified to contain the filename of the debug info file, as well as a CRC that can be used to validate it. This doesn't currently use the checksum and relies on the usual build-id matching for validation."
The Linux kernel patch is authored by Pierre-Loup A. Griffais, a well-known NVIDIA Linux name. If looking at the patch, which can be found on the LKML, you will see: "Reported-by: Mike Sartain [mikesart@valvesoftware ]
Tested-by: Mike Sartain [mikesart@valvesoftware ]" (The email addresses in this article has been intentionally obscured to avoid having Mike's address auto-harvested and spammed.) So Mike Sartain found the kernel bug and then also tested the fix while one of the NVIDIA Linux engineers went in to fix the perf problem.
Mike Sartain is a Valve employee who has been talked about on Phoronix previously. He's part of the Valve Linux (client) team and while Valve's management style is unique and a rather flat organization, you could almost look at him as the head of the Valve Linux team. For those that apply to be on the Valve Linux team, Sartain seems to be the one that does at least the initial interviewing, he's one that I've spoken with for months about the Linux work, was a prominent hire to Valve Software last year, and last time I was in Bellevue his desk was right next to Gabe's. The former Microsoft employee from the '90s is now an Ubuntu Xfce user.
So nice job to Valve/Mike for beginning to point out bugs upstream and testing the fix; well, this article is just mainly to further illustrate that Valve is actively working on Linux for those who doubt it even after Gabe says Steam is coming to Linux this year, he's recorded as saying they're showing their Linux work to partners, the Phoronix exclusives, etc.
Since Mike Sartain is also a fan of Germany, for finding this bug and continued Linux support: Prost!
More details in this article or contact me if interested for referral or contact Mike Sartain now that his email address is known from the kernel patch.