The Slowdown of Linux

Meltdown and Spectre have cast a long shadow, not least on Linux. It has been a long, difficult process to secure the OS, and November’s kernel 4.20 release returned to the issue, but this time the performance drag on Intel systems hit hard. Sorting out the Spectre variant 2 chip flaw means putting heavy restrictions on Hyper-Threading. Previous fixes knocked off a few performance percentage points; this new fix provides the security, but tests show a performance hit of 30–50 percent on many tasks. The effect has been particularly hard on Linux servers. The cure is close to being worse than the disease. Linus Torvald has even suggested turning off Hyper-Threading.