Intel graphics vulnerability mitigation patch guts performance on older systems

Last week we wrote that Intel patched a graphics vulnerability in its processors. At the moment, the patch is exclusively available for Linux and it appears it once again involves a big performance cut.

Linux website Phoronix investigated the performance impact of Intel's mitigation for the CVE-2019-14615 graphics vulnerability. Testing was performed on an older systems with the Core i7 4790K and Core i7 3770K processors. The conclusion isn't pretty, Intel's mitigation absolutely guts performance, especially on Haswell:

When taking the geometric mean of all graphics tests ran, the Core i7 3770K was 18% lower from this lone mitigation while the Core i7 4790K fell by 42%! The mitigated i7-4790K HD Graphics 4600 performance basically put the performance in line with the pre-mitigated i7-3770K graphics performance. Haswell (or at least the Core i7 4790K) appears to get hit particularly hard, more so than the Core i7 3770K. But even the Core i7 3770K performance penalty introduced by yesterday's mitigation patches is very significant. But to reiterate, those not using Gen7 graphics but newer Gen9 (or Gen8) graphics should see minimal difference from the already mainlined mitigation on that front. It's for Ivybridge/Haswell era systems along with the likes of Valley View that are much more impacted by this vulnerability's mitigation.