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Comment by ianbertolacci | Hacker News Reader

Is there a timeout?

yes. I've got 3 cores pegged now, fan shuts off for a few seconds and if I don't say anything it bails and the fans come back.

just takes about 10 seconds.

edit: I was able to keep activating siri and have the fans off while 4 cores pegged for quite a while. I don't know if CPU throttling kicked in or not, not sure how to check.

We were also wondering about existing temperature conditions. For example, I might be running some super benchmark that pegs the core temperature high. What happens when Siri turns on? If it still shuts down the fan thats bad. I could potentially keep prompting Siri (to turn off the fan) and drive the temperature a bit higher.

I don't have an app for monitoring cpu temps right now, and don't know if there is a CLI way to do it.

I was able to keep the fan off for probably a minute before I stopped. I am interested to find out if intel's cpu throttling kicked in.

edit: installed Intel Power Gadget.

with 4 cores pegged (4 actual cores), the CPU was turbo-boosted (3.0GHz on my laptop). As I prevented the fans from running via Siri, the cpu throttled back to normal rated speed. Temperature varied by a few degrees C hovering around 99C. I did this for approximately a minute or so.

It didn't go below the rated speed (2.5GHz on my laptop).

edit2: I did it again with 4 cores pegged and 4 HT cores pegged. It didn't throttle below 2.5, but I did see that the "yes" processes were throttled back. when I glanced before stopping, they were all at 80% instead of 95+%

There's no default utility for this. There's some sysctl values for the CPU and the GPU but they don't actually give you a temperature.

There's an API for this in IOKit. Easiest way I've found to get at it on the CLI is:

    gem install istats
    istats cpu temp | awk '{gsub(/[^0-9\.]/,"",$3);print $3}'

I installed Intel Power Gadget. It's pretty nice actually, no options to configure but it's pretty useful information.

Just FYI, I had to do the following:

    $ gem install istats
    ERROR:  Could not find a valid gem 'istats' (>= 0) in any repository
    ERROR:  Possible alternatives: iStats
    $ gem install iStats
    Fetching: sparkr-0.4.1.gem (100%)
    ERROR:  While executing gem ... (Gem::FilePermissionError)
        You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.
    $ sudo gem install iStats
    Fetching: sparkr-0.4.1.gem (100%)
    Successfully installed sparkr-0.4.1
    [...]
    This could take a while...

Then, I discovered it uses sparklines for output:

    $ istats cpu
    CPU temp: 60.625°C

Which is pretty cool.

EDIT: the sparkline doesn't show here, but it's a little bar-chart histogram

and thus an exploit was born.

Ya, I cant imagine that they'd forget something like that. Certainly on my iPhone Siri stops listening, which should on the PC restart the fan.

I would be very entertained if you could melt chips with an overly patient Siri.

I'd assume it wouldn't be a timeout, but a higher temperature threshold. If the machine is on the verge of melting already then you wouldn't want to turn off the fans at all.

Thats a good point, and I hope thats what they do. Im not Mac OS familiar, can other applications ask Siri to listen in? If they pause fans regardless of temperature, then it would be interesting to see if damage could be caused by an app running hot then repeatedly going to Siri.

I bet theres a way to test their cutoff mechanism. Maybe someone could run some serious bench-marking apps (maybe more CPU bound ones) and see if Siri still kills the fan at high temperatures.

Could someone potentially damage their very expensive machine to satisfy my curiosity?

You are unlikely to cause any damage, although you might make the CPU speed throttle right down

AFAIK most systems have an emergency shutoff anyway, so if it gets too hot, the machine simply powers off. At least, my old desktop did.

If the machine is on the verge of melting already, it's likely just going to hard-shutdown below the OS level.

All this could really open them up to is a hard-shutdown, and I imagine they would have implemented this as a higher threshold, not a complete disable -- at least, it seems like a really easy problem to foresee and circumvent.

Great point. You might make it shut off, but you should never be able to damage anything, no matter how clever the OS tries to be.

Siri itself has a timeout, at which point it tells you it can't hear you and goes back to sleep.

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