Just recently, Intel announced that these older-generation processors had fallen victim to a new Dawnfall security flaw. Fortunately, Intel was quick to respond with a corrective patch. Unfortunately, this patch impacts performance, sometimes severely! Phoronix conducted a battery of tests on different CPU generations. We’re talking about Xeon Ice Lake, Xeon Cascade Lake and Core i Tiger Lake.
Dawnfall: a performance-impairing patch!
As a reminder, Dawnfall is a security flaw affecting Intel processors from 6th to 11th generation. More specifically, it attacks the AVX-2/512 GATHER instructions. These instructions can be used by malicious parties to retrieve user data such as encryption keys. To solve or mitigate this problem, Intel is releasing a patch that will have a negative impact on performance.
To measure the impact of this patch, Phoronix tested it on various software applications. The program includes deep learning with Neural Magic DeepSparse, as well as OSPray and Embree 4.1 for path tracing, Ray Tracing and other rendering operations.
Finally, the result is a drop in performance measured on the various processors. Depending on the scenario, this can sometimes be very significant, particularly on OSPRay 2.12.
Moreover, Phoronix specifies that this degradation concerns workloads using AVX-2/512 GATHER instructions. Otherwise, you’re good to go, as the patch does not affect performance. What’s more, if your rendering or other operations become too time-consuming, you can deactivate the patch. That’s what Intel promised.