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Intel's Downfall Mitigations Drop Performance Up to 39%, Tests Show (tomshardware.com)
54 points by pizza on Aug 11, 2023 | hide | past | favorite | 20 comments


Well, CPU's aren't getting much faster generation by generation, so they've gotta find a new way to make the new ones more enticing.


So after 7 generations of improving performance by 3-5% a generation nearly all of those gains have been wiped away by a single bug, and other than the newly supported architecture, instruction sets, core count and gains in raw clock speed, there is essentially no compute difference between a 6700k and a 13700k?


Intel and AMD need to be broken up by anti-trust. We hit a dead end.


Shame, guess you have to buy the next gen CPU from Intel, which will surely not have any exploits.


Except the ones explicitly included... and there are many.


For the next 2-3 years at least


Once again I ask:

1) are all these vulnerabilities being exploited in the wild today?

2) since everyone is running mitigations, no one is spending much time to exploit them, so why shouldn't I turn them off myself?

Every time there's a new vulnerability out, I ask the same question and I still don't have a valid reason why I should keep them on. Herd immunity does not only apply to viruses.

In fact, the slower our CPUs get because of these fiascos, the more performance I might squeeze out of something no one is exploiting in the wild, unless I have proof of the contrary.

Of course, this works only if I disregard anyone's opinion and do it. If everybody turns off mitigations, then I'm unprotected.


Uh wait a sec, this is a microcode update? that will just install without any notice?


If I'm reading this correctly, a Linux kernel parameter `gather_data_sampling=off` will be implemented to disable the mitigation: https://www.intel.com/content/www/us/en/developer/articles/t...


Wouldn't it make sense to use mitigations=off to turn this off?


Well, that turns off all mitigations, so I guess it depends on whether you are concerned with some other vulnerabilities such as Spectre, etc.


Probably should have linked to the source that made the efforts to produce the benchmarks: https://www.phoronix.com/review/intel-downfall-benchmarks


shouldn't we all get a refund check for 39% of the price we paid for a CPU?


Yikes.

Is AMD affected by anything like this at the moment?


Yes, in addition to the prior zenbleed/spectre series of attacks, inception is the catchy name for the latest round of AMD focused speculative execution exploits

https://www.theregister.com/2023/08/09/amd_inception/


What you want to know is ...Who gets the least drop in performance when mitigation's are on. That is a tech blog article I am willing to pay for...


For sure. Also I remember hearing the spectre patches eventually improved (which I should check)


And what about ARM architectures? (Apple Silicon etc.)


Security through obscurity. And mac/arm users are a less valuable demographic to the writers of these exploits (for now).


Might be time for per virtual cpu core speculation only cache.




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