Intel Confronts Potential ‘PR Nightmare’ With Reported Chip Flaw

Post by xeeeeeeeeeeenu » Wed, Jan 03, 2018, 8:35 PM UTC

uniformlyrandom wrote: post #331

rwmj wrote: post #5

AMD must be pretty happy about this patch: https://lkml.org/lkml/2017/12/27/2

Not so sure about that. I am reading the merge commit, and comments are pretty interesting: --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h + * On Intel CPUs, if a SYSCALL instruction is at the highest canonical + * address, then that syscall will enter the kernel with a + * non-canonical return address, and SYSRET will explode dangerously. + * We avoid this particular problem by prevent…

Post by jjwiseman » Wed, Jan 03, 2018, 8:35 PM UTC

Houshalter wrote: post #356

rbanffy wrote: post #270

Earlier quoted context omitted.

It's a good thing CPU is fairly compressible. Unless you meter it very carefully, you'll see the performance hit and it'll not impact you that much. Very few of my physical boxes are over 70% CPU utilization on a daily average. It's, however, really bad if you sell CPU cycles for a living. You just lost between 5 and 30% of your capacity. If you have a large building, you just lost part of your parking lot to the Int…

Their competitors are also affected. Also a 30% decrease is also equivalent to setting Moore's law back 7 months. A 5% loss is only setting it back 1 month. I know that's a bit of a naive calculation. But the point is computing power has long operated in an exponential domain. So big differences in absolute numbers aren't necessarily a big deal.

Post by ClassyJacket » Wed, Jan 03, 2018, 8:36 PM UTC

cdoxsey wrote: post #239

ComodoHacker wrote: post #233

Earlier quoted context omitted.

Forgive me my ignorance, but I fail to see how this is such a big deal. Even 50% performance hit/cost increase would be... bearable, computations are rather cheap today. ML and other intensive calculations aren't done on CPU anyway. It's not like technical progress of our civilization is slowed down by 30% or something... On the other hand, shrinking Intel's market share due to bad PR and thus adding some competition…

If you run things efficiently you're eaking every ounce of performance out of this hardware. A 30% performance hit means a 30% cost increase. The bigger issue is for things that don't scale easily. That sql server that was at 90% capacity is suddenly unable to handle the load. Sure that could've happened organically, but now it happens (perhaps literally) overnight for everyone all at once. Expect a bunch of outages…

Post by bpchaps » Wed, Jan 03, 2018, 8:38 PM UTC

chrisper wrote: post #357

bpchaps wrote: post #134

Earlier quoted context omitted.

Spreading of information is a good thing.

It's not information. It's speculation.

Post by viraptor » Wed, Jan 03, 2018, 8:40 PM UTC

btilly wrote: post #382

viraptor wrote: post #368

Earlier quoted context omitted.

If they really care about peak performance, I don't believe the PTI patch will affect them. If you can change your system in a way that the power-hungry part does not work on untrusted data, you can not with "nopti" and ignore it. Systems which both need lots of maxed-out CPUs and traffic directly from wild internet are pretty rare. They're unlikely to run on a virtualised systems either.

Systems which both need lots of maxed-out CPUs and traffic directly from wild internet are pretty rare. That's a good description of basically every cloud environment out there, from AWS on down. In other words they are extremely common.