steviewevie
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Re: How slow is it?

Tue Mar 13, 2012 1:17 pm

Grumpyoldgit said:


At the moment there does seem to be a bit of an issue with Fedora Remix 14 but I am sure I saw something about a version 17 Remix being planned.


Not just that, but it sounds like an updated Remix 14 is in progress. From Chris Tyler's post on the front page :


The Fedora ARM project is hard at work building Fedora 17, which we hope to release concurrently with the PC versions in May. This should be the most complete Fedora ARM release produced to date.

Students in the SBR600 course at Seneca College are working to on an improved version of the Remix incorporating files from Fedora ARM 17, and this will also be released in May.



I interpret that second paragraph as an "R2" of 14, with back-ported R17 stuff.

jbk
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Re: How slow is it?

Tue Mar 13, 2012 1:54 pm

Wayland is going to be based on OpenGL ES 2 isn't it? Maybe we can skip X entirely?

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ArborealSeer
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Re: How slow is it?

Tue Mar 13, 2012 1:59 pm

JamesH said:


ArborealSeer said:





so really.. no one is currently looking at it, and its expected/assumed that someone skilled enough, will do it off their own back gratis?


Yup. That's how a lot of OSS works. Although like I said, there may be a prize.


oh I know that, but this seems to be breaking from the mould as far as the architecture in that post i found goes.. which makes it harder?

upside, such a development would have wide implications across so its "worth doing" (tm).

since anyone going down the road might find it handy, are there links for those previous projects?
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rmm200
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Re: How slow is it?

Tue Mar 13, 2012 2:00 pm

It seems very nebulous if, when, and how much the GPU is being used.

Are there any tools available to track how busy the GPU is?

It would be useful to have some way to monitor it, just so we know if our code changes are actually causing GPU activity.

What GPU related files does Broadcom provide, and what has to be specified in Linux .config to get them included?

jamesh
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Re: How slow is it?

Tue Mar 13, 2012 2:06 pm

rmm200 said:


It seems very nebulous if, when, and how much the GPU is being used.

Are there any tools available to track how busy the GPU is?

It would be useful to have some way to monitor it, just so we know if our code changes are actually causing GPU activity.

What GPU related files does Broadcom provide, and what has to be specified in Linux .config to get them included?


If you use video decode, you use the GPU, if you use the OpenGL or OpenVG libraries you use the GPU. In addition, the GPU is doing a small amount of stuff all the time to drive the HDMI output, and also move the frame buffer from Arm space to GPU space for display.

Basically, if you are writing a driver for X that uses the OpenGLES library supplied, you will be using the GPU, as fast as it can go for the particular OGLES command given.

The accelerated libraries should be supplied as standard with the distro's.

There are no tools available to the public that monitor the GPU. Might be worth knocking one up though....
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carlosfm
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Re: How slow is it?

Tue Mar 13, 2012 3:20 pm

Gents, USB controllers are resource hogs.
If you put several devices on one USB controller (keyboard, mouse, network, disk/SD card...) and much depend on it, some lockups are natural to occur.
Even worse, what if the USB controller is sharing the same IRQ with the video chip?
Probably this must be looked at, and probably some fine tuning of the latency of the several devices must be made in the operating system.
I don't have a Pi yet (it's ordered from RS but no delivery date yet), so I can't help much.

PS: 1+1??
Do you Pi?

jamesh
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Re: How slow is it?

Tue Mar 13, 2012 3:38 pm

They don't share any IRQ's AFAIK.
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carlosfm
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Re: How slow is it?

Tue Mar 13, 2012 5:06 pm

I don't know the ARM architecture... yet, the RPi either, and you must be right.

But still, device latency could be optimized.

For instance, the proprietary NVIDIA linux drivers have huge latency set as default, which in some cases generates audio glitches when watching video.

And if you pass your (USB) mouse on top of the video, it gets sluggish.

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Bakul Shah
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Re: How slow is it?

Tue Mar 13, 2012 5:06 pm

Does Arm6 have a cycle count register? You"d need something fine grained like that to accurately measure interrupt latencies and such.

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Gert van Loo
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Re: How slow is it?

Tue Mar 13, 2012 5:45 pm

Bakul said:


Does Arm6 have a cycle count register? You"d need something fine grained like that to accurately measure interrupt latencies and such.



Yes, it is one of the processor's special register. I have even used it.

Bakul Shah
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Re: How slow is it?

Tue Mar 13, 2012 6:50 pm

Thanks, Gert. I later discovered oprofile can use performance counters and it already works on Arm. See for instance http://oprofile.sourceforge.ne...../examples/ Might be worth profiling the kernel with it.

spurious
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Re: How slow is it?

Tue Mar 13, 2012 9:32 pm

Starter for 10:

http://www.x.org/wiki/DriverDe.....VideoHOWTO

Sounds so simple!

well... maybe not, but at least there is some documentation...

might need someone with more knowledge of writing video drivers or the OpenGLES

rmm200
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Re: How slow is it?

Tue Mar 13, 2012 9:32 pm

oprofile won't pick up GPU activity - but I am guessing it will at least show if the GPU interface routines are being called and how often? That could be very useful.

dom
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Re: How slow is it?

Tue Mar 13, 2012 9:33 pm

JamesH said:


There are no tools available to the public that monitor the GPU. Might be worth knocking one up though....



Actually we include vcdbg whch can extract debugging information (e.g. logs) including the task history of GPU (which will show the sleep time).

However I know what it will be when running LXDE (or other unaccelerated ARM code) - 99% idle.

There's also some OpenGL ES extensions that can extract 3D performance information - I'll look into enabling them.

But I'll be impressed by anyone who writes ARM code that can keep the GPU 100% busy. Generally if performance is low, you will fix it by optimising the ARM side, not the GPU side.

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