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Intel CPU flaw leads to kernel redesign, slower performance

Just what performance implications are the Intel CPU security flaw, and subsequent kernel rewrites, going to have for gamers?

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Just what performance implications are the Intel CPU security flaw, and subsequent kernel rewrites, going to have for gamers?

Thanks to my old mates over at The Register, we now know there’s a fundamental security flaw in modern Intel processors.

It is understood the bug is present in modern Intel processors produced in the past decade. It allows normal user programs – from database applications to JavaScript in web browsers – to discern to some extent the layout or contents of protected kernel memory areas.

That’s bad news. That’s really bad news. It’s such bad news that both Microsoft and the various Linux distributions have been working on kernel updates for the past couple of months, to prevent programs from accessing this leaky area of kernel memory.

The fix is to separate the kernel’s memory completely from user processes using what’s called Kernel Page Table Isolation, or KPTI. At one point, Forcefully Unmap Complete Kernel With Interrupt Trampolines, aka FUCKWIT, was mulled by the Linux kernel team, giving you an idea of how annoying this has been for the developers.

The upshot for most users – enterprise shops aside, who will have much larger estates and greater security concerns – is that operating system updates will be made available, very soon, to squash this bug. This will be in the form of ‘patch Tuesday’ Windows updates for most of us, or critical kernel updates for Linux folk. You just need to install the update and the issue goes away. [Please do install the updates, don’t put them off ad infinitum – InfoSec Ed.]

Unfortunately, however, that’s not likely to be the end of it. Because the kernel rewrites are effectively separating the processes from the kernel’s memory, it’s going to slow these Intel CPUs down by some degree, as the CPU has to do more work – or at least, more discrete steps – to achieve the same operation.

We don’t know exactly what performance hit this will have, and the degree will vary from one application to another, but you can guarantee gaming performance (within both Windows and Linux) is going to take a hit on Intel CPUs. El Reg, based on some initial benchmarking – albeit on non-gaming applications – reckon it will be anywhere between 5-30% .

That’s pretty huge in a sphere like gaming, with fine performance margins at play and punters paying top-whack for the subjectively best products, like modern Intel CPUs. Similarly on mobile and laptop platforms, where thermal concerns mean processors are already pared back, this could have a big knock-on effect.

This flaw needs fixing, of course, but putting security concerns aside for a moment; given the recent class actions – around VW diesel emissions and Apple battery throttling, to name just two – you can be damn sure people will be beating down Intel’s door for rebates and refunds if the performance hits are severe.


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Tom is an itinerant freelance technology writer who found a home as an Editor with Thumbsticks. Powered by coffee, RPGs, and local co-op.