When using all 4 cores at once causes it to overheat and shut down…
Yes, I know, hardly anyone runs all the computer cores at full rated capacity all the time. But…
Some folks do, and to have a machine advertized at being a speed, when it can only do that for a little while, is a flat out lie.
So what has my panties in a bunch?
A couple of times, but not too often, my computer had gone into hibernation “unexpectedly”. I figured I had jiggled the “closing laptop lid” switch or something; though did notice that a couple were when the exhaust port / bottom of the computer were a bit warmer than usual. OK, use better habits in how the thing is placed on a desk instead of on a quilt… or something…
So now I’m in a far away place, using the proper writing desk in the hotel room, and I find out why it shuts down unexpectedly. It isn’t me, or the quilt, or anything else. It’s a computer than can’t walk and chew gum at the same time if that means using all the CPU cores at once.
A check showed that the HP Forum has the story too, and with an HP Tech trying to be helpful, in that annoying not quite helpful “due to not acknowledging they have a problem” kind of way.
What brought this about was a long trail of technical interest, that I’ll relate in short form below. But suffice it to say that I’d decided to run the Litecoin code. Litecoin is a Bitcoin analog. Similar code and similar idea, slightly different technically. It is still in the ‘early days’ of “mining” coins, so reasonably easy to do. (Bitcoin is now hard enough to only be ‘worth it’ with dedicated special hardware). So I figured “I’ve got a computer just sitting here in the hotel room, with free power, why not let it mine Litecoins?” If they ever have a value, I can trade them for something… (Presently trading at about $4 each I think.)
So I installed it. Fired it up. Ran fine for hours (downloading the list of ‘blocks’ that have already been processed / mined). A CPU light, network limited, task. Then I started “mining”. This is a CPU intensive search for a short hash value for a given block. I’ve got the CPU monitor running. I see all four cores go to 100%. Nice. 2700 range of “hashes per second” is not too shabby. Then my machine goes into hibernation. (i.e. shuts down to ‘sleep’ mode). Repeat a few times. Stop mining and leave the CPUs at nearly idle? No problem.
Basically, you can run the 4 cores of the CPU at 100% for about 1 to 2 minutes, then the thing is overheated and goes to sleep.
I’d guess that the “duty cycle” is about 50%. This is basically a 2 core at a time box.
Did HP think nobody would notice? Do they not have a QA department that actually stress tests things? With an “overheat” problem in a 72 F air conditioned room, what will happen on a 100 F job site? (Forget it if at 120 F+ places… )
Laptops are mobile devices that go to all sorts of hot places to be used. Like vehicles in the sun. Buyers of a 4 core CPU laptop expect that they can actually USE the 4 cores of their CPU, and all at the same time… for more than 60 seconds… It is very easy to make a benchmark that runs a machine at 100% of CPU for a couple of hours. Do it.
OK, back at the rant:
Worse, there doesn’t seem to be any way to say “At FOO degrees F, slow the clock on the CPU to reduce heat” or even “Run at 75% of max CPU.”
So, much as it pains me to say it, I can only say that the HP Pavilion G6 laptop is a cheap machine with poor testing that lies about what specs it can actually reach. It has an overheating problem that HP Support Forum is unwilling to recognize / admit. It is easily demonstrable (install Litecoin, start mining) and easily stopped (don’t use more than 50% of the processor capacity). This is as close to a “no brainer” as you can get. I just diagnosed it in 10 minutes in a hotel with no outside support ( I put “HP pavilion G6 overheat shutdown” in as a search term and that pulled up the “Support Forum” – along with many other hits… so clearly I’d figured out what the issue was in order to make the search term string.)
OK, THIS laptop is now a “lite use only, don’t want to overheat the little dear” and I’m in the market for a different solution.
Related: I’m plugging in my Raspberri Pi to see if the Linux “Litecoin” install works on it. Then the Laptop can do something it is well suited to doing: be a dumb terminal server. Don’t want to stress the CPU after all…
At work, I’d told someone about the R.Pi which lead to mentioning the Epiphany Chip and the Parallella board. I’d mentioned it in this article:
That has this link:
Down in the weeds of some story about it, I found an “update” saying the boards where now being shipped to the early group, and that one project was to put scrypt on it. Why? I wondered… Turns out scrypt is the method used by Litecoin. OK…
The other student accepted for Parallella related tasks is Rafael Waldo Delgado Doblas, also known as lordrafa. Rafael’s tasks include addition of scrypt support to John the Ripper using host CPU, experimenting with scrypt time-memory tradeoff, and then implementing scrypt cracking on Epiphany making use of the tradeoff (to fit in each Epiphany core’s 32 KB of local memory regardless of scrypt’s actual settings). Considering that scrypt on Epiphany makes little sense except at very low memory settings (where having to use the tradeoff doesn’t result in too much of a slowdown), the likely next task for Rafael is to implement Litecoin mining on Epiphany. Luckily (for this task), Litecoin uses scrypt at as low as 128 KB, which translates into only a ~2x expected slowdown when we reduce the memory needs to below 32 KB.
So this thing can become one heck of a Litecoin mining device. That gets me wondering about Litecoins.
As a sidebar, making a hashing engine that’s massively parallel and precomputing a lot of hash values has “benefits” for cryptanalysis, so part of me wonders if this is just an interesting clandestine way to get a lot of crypto work done for free… and a lot of neat dedicated hardware designed for cheap… but that’s just the Systems Admin Professional Paranoia talking… Yet it WOULD be a good board for attacking passwords and encrypted files….
So back at Litecoin:
I decide it might be interesting to “give it a whirl” and see how long it takes to “mine” a “coin”; then “do the math” and see if buying one of these boards could pay for itself in reasonable time. Thus the “install to mine one coin and measure”. Thus the overheating problem demonstration.
Oh Well, as they say.
I’d run into some pages on “mining” (where folks look to band into “pools” so they are more efficient, I think) and how to custom build “rigs” that do nothing but this compute problem. Some folks seeming to have even less of a life that I do… Well, at least I can enjoy knowing that I’m a little less geeky than some, and with a few more interesting things to do most of the time.
Which links to a page with an interesting use of “Milk Crates” to house board based cluster computing:
You can even do it on a Mac:
Just not on an HP Pavilion G6 Laptop…
Well, I’ve got my old Mac along on this trip (figuring that “someday” I’ll have some downtime to finally move everything off of that hard drive and onto removable media). So I suppose I can put a Litecoin mining rig on it for testing. It’s a decade or so old, but still works fine (even at 100% CPU utilization…) so might as well.
I’ve also got 2 Raspberry Pi boards with me. One is my DNS / Bittorrent server. Since the hotels all seem to be blocking bittorrent and redirecting DNS, It’s not all that usable right now. (Eventually, when I get more long term lodging, it can go back to the primary job). So a 4 GB SD card and it can have a new personality mining Litecoins.
Not exactly the project I’d thought I be reporting on tonight, but such is life.
The Raspberry Pi has a sensor in the CPU. When overheat point is reached, it automagically dials back the clock speed to hold the temp line. You keep on running, but just slow down to that rate which is the max you can do. (Overclockers use this as a self setting max clock feature, so overclock like crazy and let the CPU ramp back down to “at the limit”.)
It is a remarkable thing to realize that a $25 “toy” computer on a card has better thermal management behaviours than an H.P. Laptop. Maybe someone ought to send H.P. a R.Pi card with thermal data attached.
OK, I’m behind on finding out if mining Litecoins is interesting at all, so really need to get the R.Pi plugged into the HP as a dumb terminal and redo the work from last night of getting the software downloaded and installed and running.
I’m also thinking that maybe what I need to do is just order one of those Parallella cards and use it to build my own “laptop”. 32 GB SD card. USB TB hard drive. Bluetooth keyboard and mouse. Just need to work out a nice way to attach a display and battery box. Oh, and GOOD ventilation… Aluminum is very cheap, and conducts heat better than air. Silent too. Just saying.
Well, don’t want to overheat the laptop, so I need to give a bit of a rest. After all, it’s been using at least one of it’s 4 cores for an hour or so now. Don’t want to push it…