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iPhone update for Meltdown-Spectre: before/after performance benchmarks

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Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#21

Post by JoachimSchipper »

2bitencryption wrote: post #11

this leads me to a couple questions, hopefully you smart folk can answer: 1. I thought Spectre was "Intel-only", and Meltdown was the general case, which is less severe but effectively nearly everywhere? If so, how is an iPhone susceptible to Spectre? 2. Beyond that, I thought meltdown/spectre was an x86 problem. So why all this trouble on phones, with ARM? 3. I've read the first, simplest variant of meltdown, and it…

1: Spectre is the general case, Meltdown is the Intel-only evil cousin.

2: Spectre applies to all modern processors with speculative execution, which includes smartphone-class ARM processors. Raspberry Pi's and microprocessors ("toasters") are not affected.

3: There's some prior work - Spectre didn't fall from thin air - but using speculative execution as the basis of an exploit makes Spectre the first bugs in, I believe, a new class. (Meltdown, on the other hand, is just a silly mistake that shouldn't be repeated.)

Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#22

Post by sschueller »

Is the Samsung S8 CPU also affected? I saw that some ARMs are not affected.

EDIT: It appears not the be on the list of affected ARMs [1]. The S8 Exynos 9 Octa 8895 is based on the Cortex-A53

[1] https://developer.arm.com/support/security-update

EDIT2: The Snapdragon 820 and 835 do appear to be affected which are the CPU in the US version of the S8

Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#26

Post by JoachimSchipper »

sschueller wrote: post #22

Is the Samsung S8 CPU also affected? I saw that some ARMs are not affected. EDIT: It appears not the be on the list of affected ARMs [1]. The S8 Exynos 9 Octa 8895 is based on the Cortex-A53 [1] https://developer.arm.com/support/security-update EDIT2: The Snapdragon 820 and 835 do appear to be affected which are the CPU in the US version of the S8

Assume that [EDIT: high-end - dogma1138 is right] smartphone-class processors and above are affected. Raspberry Pi and microcontroller-class ARMs are fine, though (but much slower!)

Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#27

Post by StringyBob »

intopieces wrote: post #16
StringyBob wrote: post #10

Wow. After ios 10.2.1 halved performance on my iphone 6 due to the battery issues, I next avoided 11.0 as I accepted responsiveness would be slower on the older iphone6 model. Now if we want these security fixes that's another -40%... Yikes! However, it looks like ios 11.2.2 and a new battery is still slightly faster than ios 10.3.3 and an old battery! (geekbench single/multi core score from article of 924/1616 vs my…

I don't understand this logic at all. The fixes are being made for a reason... avoiding the update just means you are getting more performance for a less secure system. Are you betting on a law of averages to break in your favor? Hoping you're not a target of hackers? what am I missing with this strategy?

Just that I could be looking at a > 75% performance reduction on the same phone compared to when it was new due to the combo of battery degradation, security fixes and ios9 to ios11 general slow down.

I think that if they've disabled some cpu core features that might reduce the maximum power loading anyway and make the double whammy impact of security and battery related slowdown unnecessary.

Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#28

Post by untog »

intopieces wrote: post #16
StringyBob wrote: post #10

Wow. After ios 10.2.1 halved performance on my iphone 6 due to the battery issues, I next avoided 11.0 as I accepted responsiveness would be slower on the older iphone6 model. Now if we want these security fixes that's another -40%... Yikes! However, it looks like ios 11.2.2 and a new battery is still slightly faster than ios 10.3.3 and an old battery! (geekbench single/multi core score from article of 924/1616 vs my…

I don't understand this logic at all. The fixes are being made for a reason... avoiding the update just means you are getting more performance for a less secure system. Are you betting on a law of averages to break in your favor? Hoping you're not a target of hackers? what am I missing with this strategy?

The OP doesn't seem to suggest that they won't update, just that there is a considerable price to be paid in doing so.

> Are you betting on a law of averages to break in your favor? Hoping you're not a target of hackers?

Aside from anything else, I wouldn't be at all surprised if some people do take this gamble. They shouldn't, but if they're informed about it then it's in their own hands.

Re: iPhone update for Meltdown-Spectre: before/after performance benchmarks

#29

Post by qeternity »

intopieces wrote: post #16
StringyBob wrote: post #10

Wow. After ios 10.2.1 halved performance on my iphone 6 due to the battery issues, I next avoided 11.0 as I accepted responsiveness would be slower on the older iphone6 model. Now if we want these security fixes that's another -40%... Yikes! However, it looks like ios 11.2.2 and a new battery is still slightly faster than ios 10.3.3 and an old battery! (geekbench single/multi core score from article of 924/1616 vs my…

I don't understand this logic at all. The fixes are being made for a reason... avoiding the update just means you are getting more performance for a less secure system. Are you betting on a law of averages to break in your favor? Hoping you're not a target of hackers? what am I missing with this strategy?

All of these issues require local execution. It’s perfectly fine for many single user, performance critical use cases to make this type of security trade off.
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