maemo.org - Talk - Mobile System on Chip Thread

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Quote:

Originally Posted by shadowjk (Post 929072)

Are those quad still going to be the most castrated and crippled A9s like in current Tegra?

Please explain. I'm interested in what you mean by 'crippled'.

Citing the "Benefits of multi-core CPUs in mobile devices" whitepaper released by Nvidia, multi-core CPUs might actually be more power efficient:

Quote:

Due to task sharing, the cores don’t need to run at full capacity and can be run at a lower
frequency and voltage. Since the power consumption of semiconductor devices is proportional
to the frequency and voltage-squared, even a small reduction in the operating frequency and
voltage will result in significant reduction in power consumption. Therefore a mobile processor
with a dual core CPU with SMP capabilities will often be more power efficient than a single core
CPU based mobile processor.

Also, there are situations when you need all peek horsepower you can get - like during application startup (no one likes to wait).

More cores make multiprocessing more seamless, not only in relation to running multiple applications simultaneously but also for single applications - make one thread run a lag free GUI and other thread/s can do all the needed time intensive data processing and computations in the background. All of this is easier when you have multiple cores.

Nvidia has released a whitepaper for it's ULP GeForce GPU line, citing advanced features and outstanding performance.

There is no mention of Tegra 3 (AFAICT), but this should give some insight into their future direction as well as a high-level perspective of architecture design.

http://www.nvidia.com/content/PDF/te...ld_Devices.pdf

The Tegra 3 will be a force to be reckoned with. I fully expect NVidia to hold the lead as they are planning yearly releases! :eek:

Quote:

Originally Posted by MartinK (Post 929327)

More cores make multiprocessing more seamless, not only in relation to running multiple applications simultaneously but also for single applications - make one thread run a lag free GUI and other thread/s can do all the needed time intensive data processing and computations in the background. All of this is easier when you have multiple cores.

When you put it this way, it's a spin. Multiple cores make none of this easier. More efficient ? Yes, depending on use-case. Easier ? Not in any way. You still need to do thread/task separation as you would do it on a single core processor. Beyond that, it's all about priorities (yeah, if only iOS was snappier and did not have these laggy, 10fps animations... oh wait). I mean, Android and iOS both downplay multitasking because they don't really trust developers can deal with resource management. And suddenly someone says that they will write perfectly balanced multithreaded deadlock-free code, which is rocket science compared to memory management and such. Multicore will have it's uses, but not in this sense. I have no qualms that these will be snappier, but that will be more to the A9 design and upped graph chips, not multicore - but that is what will get hyped as it's an easier sell (we already see vendors linearly adding up clocks and MIPS).

Quote:

Originally Posted by funkmunk (Post 928442)

I wouldn't trust NVIDIA with that as i think they pretty much screwed up they're PC GPU cards with the heat issues. Im not sure how well the Tegra chips fare in the battery department.

But if there is a chip im waiting to get my hands on then that has to be the ST-Ericsson U8500 SoC. That is one hell of a chip...

no doubt nvidia has serious heat issues.once they posted a driver update which slightly overclocked your gpu while turning off its fan!!! which resulted in my 9800gtx+ being fried all over.

Quote:

Originally Posted by attila77 (Post 930066)

When you put it this way, it's a spin. Multiple cores make none of this easier.

I might have used a bad formulation - multi-threaded programming is of course not easy at all - but once you have a working program that uses multiple threads, it might benefit from running on a multi-core CPU.
I'd also guess that the more cores are available, the less one has to worry about about the threads contending for a single core (like a background worker thread starving the GUI thread for CPU time, causing the GUI to lag).

Quote:

Originally Posted by attila77 (Post 930066)

I mean, Android and iOS both downplay multitasking because they don't really trust developers can deal with resource management. And suddenly someone says that they will write perfectly balanced multithreaded deadlock-free code, which is rocket science compared to memory management and such.

I know this isn't related to the argument but I thought it worth posting.

I'm not sure what you mean by 'downplay', but Android uses explicit events to separate process-level multi-tasking concerns and gives the OS the ability to choose what to do with the process once backgrounded based on its configuration. This is certainly more complicated than the brute-force approach to simply having the kernel handle task scheduling treating all processes as more-or-less equal and in no way 'downplays' it. It also gives developers explicit control over what parts (if any) are put to sleep when the app loses focus and allows them to run their own code during these events. This is a boon to battery life and performance; upon losing focus, only key code can remain running in the background while other code is shut down. Consider how long our laptops would run if such event separation were included in applications from the get-go!

<offtopic>
But arguably the largest benefit of such a system is not having to explicitly close applications (well, the ones that are coded properly anyway) -- one of the great features of palmOS of old. When the OS needs resources, it can dump idle processes and state save. For apps that are intended to be backgrounded, the developers simply need structure the application accordingly and the app will continue running in the background.

But the problem is as you say: many developers (including google's own) seem not to use the facilities properly leading to bad resource utilization and the need for task killers. It seems, as always, the additional layer of complexity introduces the chance to err at an increasing rate.
</offtopic>

What the Sony NGP has pwns the Tegra3!
XD

Quote:

Originally Posted by Kangal (Post 930403)

What the Sony NGP has pwns the Tegra3!
XD

are you serious or is that just flamebait? they're both quad core a9's. or maybe the psp 2 has dual dual-cores. i'll give you the benefit of the doubt and assume you're talking about the video... but with no specs on the tegra 3 i wouldn't be so quick to pass judgement.

Quote:

Originally Posted by Capt'n Corrupt (Post 929109)

Please explain. I'm interested in what you mean by 'crippled'.

There's no NEON, and it has half the registers. First MeeGo versions actually didn't work on it, but now they've begun compiling meego to be able to run on it. It probably makes it a bit slower on omap3 and omap4 though :)