INSUBCONTINENT EXCLUSIVE:
Ubuntu users could see up to a 20 percent boost in graphics performance on Intel-based systems under a change that will turn off security
mitigations for blunting a class of attacks known as Spectre.Spectre, you may recall, came to public notice in 2018
Spectre attacks are based on the observation that performance enhancements built into modern CPUs open a side channel that can leak secrets
The performance enhancement, known as speculative execution, predicts future instructions a CPU might receive and then performs the
corresponding tasks before they are even called
If the instructions never come, the CPU discards the work it performed
When the prediction is correct, the CPU has already completed the task.By using code that forces a CPU to execute carefully selected
instructions, Spectre attacks can extract confidential data that the CPU would have accessed had it carried out the ghost instructions
Over the past seven years, researchers have uncovered multiple attack variants based on the architectural flaws, which are unfixable
CPU manufacturers have responded by creating patches in both micro code and binary code that restrict speculative execution operations in
These restrictions, of course, usually degrade CPU performance.Over time, those mitigations have degraded graphics processing performance by
as much as 20 percent, a member of the Ubuntu development team recently reported
Additionally, the team member said, Ubuntu will integrate many of the same mitigations directly into its Kernel, specifically in the
Questing Quokka release scheduled for October
In consultation with their counterparts at Intel, Ubuntu security engineers have decided to disable the mitigations in the device driver for
He continued:At this point, Spectre has been mitigated in the kernel, and a clear warning from the Compute Runtime build serves as a
notification for those running modified kernels without those patches
For these reasons, we feel that Spectre mitigations in Compute Runtime no longer offer enough security impact to justify the current
