News Nvidia talks up dual-core power saving

http://www.bit-tech.net/news/hardware/2010/12/08/nvidia-dual-core-power-saving/1

 

that's cool.. like professional juggling

 

did they actually test it or did they just do the calculations? I learned a long time ago not to trust mathemeticians...

 

from my experience with journals, nVidia used ............. Maths.

(it's pretty hard to achieve Prof Farnsworth's effect in latest Futurama season using text)

 

Didn't Tegra2 get dropped by Boxee when they were making their set-top box cause it couldn't run all 1080p formats?

In any case, to get this kind of performance, you'd need really stringent and complex power draw flows both on the hardware and in the OS. I am unsure that the power saving can actually be maximized as perfectly as it is laid out here.

 

i've thought of this about a full year before nvidia came up with this idea, and it really works. but, theres 1 problem with it. since using 2 cores can reduce the amount of cpu utilization which therefore reduces the frequency, which allows a lowered voltage, if the 2 cores end up being maxed out, then they use up significantly more power and cause more heat (and heat makes electricity less efficient), which therefore makes the 2 cores less valuable. if people have a more powerful device, they're going to want to take advantage of it. also, if both devices are idled, the dual core will still use up more power since it (theoretically anyway) has more electronics inside, which adds up electric resistance.

as i see it, the key is multi-threading. that would help reduce the amount of cpu usage without adding more electronics. unfortunately, the pentium 4, i5, and i7 are currently the only CPUs capable of that and its taken about 10 years for amd to finally invest in it, so i doubt we'll be seeing any arm chips doing this any time soon.

 

Depends on how well programmed the software is. What if said dual core wanted to run everything on one core and let the other idle?

 

thats an excellent point but, depending on how the OS handles the process, it could be divided between both cores, making them used at 50%. this doesn't stress them enough to make them use too much more power.

 

Personally I think the advantage would come from having more processing power per area like combining CPU with GPU, more cores is easier than IPC or increasing frequency. It really just reopens the faster single core vs slow dual core debate. The point that would make more sense sale wise is

completion time X Power per min = power useage

They've went about proving "dual > single" core in a weird way.

 

In that case, you;d have to have a way to actually shut off voltage to the second core. As long as you have each core on different supplies, theoretically some control system could be developed to shut down a core if, say, the phone is in a lock/idle state.

 

yeh dual core CPU in mobile devices then next year 4 core cpu in mobile devices and then
in 2013 we will get mobile devices with pci-e slots, water blocks, neon lights, and plexiglass cases.
meanwhile the iPhone 5gs WiMax version 2.0 will be as thin as a credit card with a magnetic strip on it and you will literally just swipe it to give Apple free money.

muha hah ahh ha haaa.

 

I don't know precise numbers, but since all current ARM architectures are fully power gated (or at least mostly, if I am simply crossing a new SoC with the current SoCs), two cores doing nothing is still going to draw zero power.

As for both cores going full whack, well, that is a possibility. However, as mentioned, it all depends on the software. If checks are not in place to make sure software doesn't use more resources than it needs, then you could very quickly be running for the power outlet.

An argument I see a lot on the internet is that while a lot of the more powerful CPUs (or CPUs with more cores) may draw a lot more power, they finish whatever task they are doing a lot quicker. It often works out more efficient to use two cores and finish the task in less than half the time. When comparing using things like loading, compressing, and other finite tasks, this makes perfect sense to me; two cores drawing nothing still equals nothing, and if the two cores are finishing tasks more than twice as fast, well, we have a winner.

Thing is, apart from the loading and responsiveness of phones, which obviously would benefit from this kind of upgrade, people very rarely spend much time waiting for such tasks, and instead will be playing games or watching a movie on their phone. These tasks, unless controlled to only use what they need, would utterly destroy any good that the upgrade to dual cores achieves, at least in terms of battery life.

To be fair, I do think multicore CPUs in phones is a great idea, but as we often see in the tech industry (especially recently), the hardware can be the dog's bollocks, but if the software doesn't make use of it correctly, well, it's pretty useless.

At the end of the day though, the screen is by far the most power hungry component of any phone (and let's not forget the cell radio), so all of this talk is pretty moot when you start looking at the phone as a whole.

 

Hmm, i wasn't aware of the power grating, so i guess that nulls that argument haha.
i completely agree on what you said about more cores completing tasks quicker, but keep in mind that usually if you're doing a strenuous task on a mobile device; it isn't going to be something with a fixed goal, such as encoding a video. typically strenuous tasks on mobile devices will be games, where they might want to be played for longer than the battery life supports.

i too think its a good idea for multicore CPUs to be in phones, but it really comes down to how you use your phone. if you want good battery life and don't do anything complicated, a dual core is great. if you do strenuous tasks and you care about battery life, get a single core (most apps are designed for single cores anyway so its not like you're really missing out). if you multitask and you don't care about battery life, get the dual core.

if companies really want to get better battery life with screens they need to invest in OLED screens

 

TBH the nature of the way phones are used, ie constantly doing something simple, I can't see battery life improving short term. while a 1GHz chip is more than plenty for a phone, people are starting to demand more from their device weather it be faster games, prettier graphics, 1080p etc. Look at the tablet market and upcoming PSP phone. they will most benefit from faster processors but like intel and AMD discovered, you can't go down the route of raw MHz forever otherwise power useage and heat will get out of control. ARM and VIA are both committed to highly efficient processors so regardless if they stay single or dual core but like I said above, theres only so far you can go with IPC and MHz. Dual cores will happen and this is what Nvidia are really pushing for possibly earlier than other companies, since their main market is GPU which uses highly parallel design to achieve its performance. All companies can benefit from lessons learnt in the ULV market.

Everything is becoming more efficient but the smart phone and ultra portable market are still trying to get enough speed while using the same size battery. 1GHz is just about enough for what a smart phone does, but again games and people who want 1080p output will always ask more. I totally agree tho, the biggest power savings will come from new screen technology. Sinking crazy billions to gear FABs for the next process is soon coming to its EOL.

 

Very interesting article. From the people that make the most power-hungry video-cards in all existence!