My Thoughts on the Pyra


The TI OMAP5 EVM has 2GB of RAM, which is implemented using 4x Micron 4Gb DDR3L devices (MT41K256M16HA-125:E).

DDR3L operates at 1.35V and each of those 4Gb (512MB) chips draws 20mA if it is doing nothing more than self-refresh. So when idle, 2GB of this type of RAM should consume about 1.35V * 20mA * 4 = 108mW.

For comparison, with the lid closed and cpu idle, a Pandora uses slightly less than 100mW. That number includes not just its 512MB of RAM but also all the other stuff.

The Pyra battery will be bigger than the Pandora one, and the Pandora has a standby time of about 7 days (4200mAh * 3.7V / 95mW).

Let's say a 2GB Pyra uses 150mW when standby (108mW for RAM and the rest for the other stuff). With a 6000mAh battery that results in 6 days of standby time.

If the same type of RAM is used, 4GB will consume twice as much, so let's say the total is 250mW. In that case, standby time is reduced to less than 4 days.

So the effect on standby time is quite big.

One potential solution would be to use suspend-to-disk instead of suspend-to-ram to achieve better standby times. But the eMMC will probably not be large enough to do that, so you would have to use free space on an SD card. The theoretical maximum transfer speed we can achieve is about 100MB/s. That means that suspending and resuming takes about 20 seconds each if 2GB needs to be transferred between RAM and SD card (it could be less because only used memory needs to be stored/restored), and of course twice as long if 4GB has to be transferred. In practice it would probably be slower than that because SD cards that max out the theoretical speed limit are very expensive. So that does not look like an acceptable solution.

I would rather spend money on more expensive lower-power 2GB RAM, than on 4GB. In general, I would like to make sure that the Pyra improves upon the Pandora in all respects, instead of having it improve some aspects (amount of RAM) by sacrificing other aspects (standby time).
4 days standby is fine with me.  Especially if we can have it set up to:

After X minutes of no use or standby switch pressed = go into standby.

After an additional hour = turn on long enough to suspend to disk.

So - there are ways to greatly increase the standby time AND the odds of being away from an outlet for 4+ days with a portable computer without turning it off is silly.

Of course the 'normal' RAM being used in the Pyra is going to consume the largest chunk of the standby resources - it's the only thing left doing anything at that point.

The numbers that would make an actual difference in this are ON and RUNNING.  How much will it hurt in -on- scenarios?

System running full tilt flat out?  OMAP5 consuming 4000mW by itself + memory 108mW Vs 4W + 216mW.  The additional memory is a blip on the power map at that point.  In this scenario double RAM might loose a few % of battery life.

System running but doing very little = music playback?  OMAP5 consuming 1W?  (What's it's operating floor?) + memory 108mW ~ 1.1W vs 1.2W with additional RAM.  In this scenario double RAM might loose 5% or so?

It may have been less of an energy impact if we had an SoC that could handle mobile/phone RAM (LPDDR3 Vs DDR3L), but we've got what we've got.

It's probably going to be 2GB and I'll be perfectly happy.
 
4 days standby is fine with me.  Especially if we can have it set up to:

After X minutes of no use or standby switch pressed = go into standby.

After an additional hour = turn on long enough to suspend to disk.
I find these kind of power saving policies on phones and such extremely annoying. On Pyra I would definitely turn off all of them.

I don't need the device telling me when to go to stand by. I'm smart enough to put it on stand by when needed to save battery. All I need is an easy to access switch/button for that feature.

Suspend to disk is completely out of the question. Takes too long, puts extra strain on storage, etc. No, just no.

So, as _wb_ puts it, stand by time needs to be great, otherwise Pyra would be a step backwards from Pandora on that respect.
 
Pyra has a quad core setup, two A15s, and two M4s.
Bullshit.
The Pyra has a dual core processor and two useless little cpus which probably won't find more uses than Pandora's DSP: Only a couple of years after release, there is a handful (i.e. less than 5) programs using it (I couldn't name any off the top of my head), which that way gain a bit of performance or use a bit less energy (in exchange for a huge amount of work on the programmers side).
They are supposed to offload tasks like handling the phone portion, so you have the full power of the A15s for other things. Also, two A15s plus two M4s makes four cores, so that is quad core. Regardless of how useless you think the M4s may be.
 
Question: Can the M4 cores be used automatically by processes on Linux? Or do programs need to be specifically made to use them?
 
I don't think so. For starters they are slightly different architectures: ARMv7-M vs ARMv7-A. I don't know enough to say for certain but I'm pretty sure that means some stuff isn't compatible, I'm pretty sure I remember someone with more knowledge about it saying so but I can't remember when or who so I'm possibly mistaken.

It's definitely not like big.LITTLE where a process can just bounce back and forth between the two CPUs as requirements change, the M4s explicitly need to have something done to them in order to use them. I suspect they're going to be a lot like the DPS on the Pandora.
 
Oh bummer, I was hoping it would be like big.LITTLE, then they would for sure see some use. Oh wells.
 
Pyra has a quad core setup, two A15s, and two M4s.
Bullshit.The Pyra has a dual core processor and two useless little cpus which probably won't find more uses than Pandora's DSP: Only a couple of years after release, there is a handful (i.e. less than 5) programs using it (I couldn't name any off the top of my head), which that way gain a bit of performance or use a bit less energy (in exchange for a huge amount of work on the programmers side).
They are supposed to offload tasks like handling the phone portion, so you have the full power of the A15s for other things. Also, two A15s plus two M4s makes four cores, so that is quad core. Regardless of how useless you think the M4s may be.
Quad core means 4 cores which can be used interchangeably, which can execute the same programs. You can't count any 200Mhz tiny coprocessor (that's what they are) as an additional core.They can only be used by programs which specifically target them. Which is probably hard. I feel my Pandora DSP comparison is valid.
 
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All I know is quad means four, and it has four. Just because two are different doesn't mean there's not four. You could code smaller applications like an internet radio player to use the M4s, and then it wouldn't take any processing power from the rest of the device.
 
All I know is quad means four, and it has four. Just because two are different doesn't mean there's not four. You could code smaller applications like an internet radio player to use the M4s, and then it wouldn't take any processing power from the rest of the device.
But by that logic the Pandora has at least a tri core processor, just count the DSP and the graphic chip too. And the Pyra has it's two real processor cores, two little co-processors, two graphics units PowerVR SGX544MP (because meaningless numbers and letters are fun), the TI 2D BitBlt graphics accelerator and the DSP, so it's octa core. Yay!11!


The problem with your example is the following: Sure, you can code an internet radio player to run on it. But it will take you huge amounts of time and you'll need to be a more advanced coder than the average great guy who is porting apps to the Pandora. You'll need to figure out access conflicts to the network chips (3G/W-LAN), to disk, to the audio output, you'll need to learn how to make your code run on the M4s at all (not as easy as it sounds, most likely), then you'll need to actually code the app, and I'm pretty sure you'll have a lot of trouble because you can neither run Linux on them (even more trouble sharing hardware components) nor access certain nice features the kernel usually provides to you, because it's running separately on another piece of the die. So you would need to code it in a very low-level fashion, which is again difficult and a huge lot of work. There is no drop in web radio player for M4s (neither are a lot of other applications, if any. Probably none).


Then, when you are finished, those M4s run a 200Mhz max. That means the task of playing a web radio station isn't such an easy task anymore, it will have to work much more than the full featured cores would have to. That means the full cores might even use less energy for the task because they could sleep (i.e. powersave) for 90% of the time while the M4s need to work for at least 70% of the time.


It's probably simply not worth the effort. They are made for other things, for example you could probably dedicate a portion of the GPIO pins to them and use them to control a machine. Say, a stepper motor driver. Or read a sensor array. Then you would work out a simple protocol for sending data for the M4s, you wouldn't need to share any hardware between them (maybe give them some RAM, but not much for a simple task) and they would just provide you with a simpler way to retrieve/send data which has already been preprocessed/will automatically get some low level processing applied to it and not have to do it in real time, you have a little buffer.


Very useful in industrial/automotive applications. Not in the Pyra.


And even in such contexts, you don't call them processor cores, but coprocessors.


Look in Wikipedia, it lists the OMAP5 as consisting of two dual core processors. That's much more appropriate.

Calling the OMAP5 quad core is severly misleading. If you don't understand the subtleties, then just believe me or ask someone else for confirmation and then believe that person, like Exophase or notaz. WizardStan has already posted a similar opinion to mine.


I might have gotten some little things wrong, people like Exophase or notaz could probably explain it better and more accurately, but the overall picture is right.

Edit: Or maybe look at it like that: M4 processors are also sold separately. When they are sold like that, they are called "micro controller" and used in products similar to the Arduino (which I hope you know, otherwise you don't need to read on the comparison). Do you really think if you slapped the guts of an Arduino onto the Pyra board that should be considered Penta core because it's A15*2 + M4*2 + Arduino microcontroller?
 
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I suppose I'm thinking too literally? It may not technically be a quad core, but from a literal standpoint it is, because the M4s are processor cores, and the A15s are. I suppose that makes more like two dual core processors in one chip then?
 
But by that logic the Pandora has at least a tri core processor, just count the DSP and the graphic chip too. And the Pyra has it's two real processor cores, two little co-processors, two graphics units PowerVR SGX544MP (because meaningless numbers and letters are fun), the TI 2D BitBlt graphics accelerator and the DSP, so it's octa core. Yay!11!
OCTA-POWER!!!

Sounds great!  :D   But you forgot to also tell the "Bits" of the OMAP5, like the old "Console Classification" 8, 16, 32, 64, 128... where do we actualy stand right now after that classification?  ^_^

Watch this video.


OMAP 5 is mind blowing.


It make you to the coolest person on earth.

https://www.youtube.com/embed/lynSWIFOcRE?feature=oembed
Cool.  B)   So in short, The OMAP5 can do everything. Do we also get such an Projector for the Pyra? "Pyra-Projector"? ;)
 
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Sometimes I type for a while, and then I find out that a tree in that forest hasn't heard of me.

Maybe I'm an attention whore....but not according to that Sequoia up there...
 
I'm still down with my Pandora....which could be the ultimute device IF you would add a SIM card.


I know that it'd add $$$ and a host of other "certification" problems....still, I think that WE/Consumers/customers want an ALL in ONE Device.  To be brutally honest.  We want simplicity, because inherently we're ALL lazy.....
 
I don't need a sim card slot/telephone capabilities, but you'd be surprised how SUCCESSFUL you/we can be when/if you bring the "telephony" aspect into the equation.   It's a question that you need to answer.  Sell to thousands or sell to millions?
 
Not that your posts make any sense, Franko, but could you please stop making multiple posts after each other you ... are annoying me.

If you put all of your ... output into one post, I could better respect your right to freely state your ... opinions and wouldn't feel the urge to ... rebuke you.
 
Could someone enlighten me as to what these m4 cores are? I thought they were just low power cores. But the ARM website says they are meant for signal processing. And wikipedia says they have DSP instructions. So are they some kind of fancy DSP?

On a different topic, I found an interesting benchmark done on an OMAP5432 board: http://www.linux.com/learn/docs/731673-tis-omap5432-board-part-2. Despite being underclocked to just 800mhz, it did very well.

Also, I found a comparison of various mobile gpus, one of which is the SGX544MP2 that the pyra uses: http://www.cnx-software.com/2013/01/19/gpus-comparison-arm-mali-vs-vivante-gcxxx-vs-powervr-sgx-vs-nvidia-geforce-ulp/
 
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Could someone enlighten me as to what these m4 cores are? I thought they were just low power cores. But the ARM website says they are meant for signal processing. And wikipedia says they have DSP instructions. So are they some kind of fancy DSP?
Please look at the previous page, I've written a lengthy post about why they aren't additional processor cores. There is also information in there what they actually are, what they are meant to be used for (in principle I give two examples for signal processing).
They are meant for industrial uses. For specialized applications. They are probably not much more efficient in terms of power/equivalent computation, but use less because they can do less than the A15 processor cores.
 
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