The Raspberry Pi Thread

[JuLieN]

Julien,

As for the speed problem, try copying this and pasting it in /boot/config.txt

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arm_freq = 900
gpu_freq = 350
sdram_freq = 500

and reboot.

**IMPORTANT**

If the raspberry pi doesn't boot up with this, turn the Pi off, remove the SD card, plug it into your computer. You should find a file called config.txt (I wonder where that came from) open it with your favourite text editor and replace

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arm_freq = 900

with

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arm_freq = 850

Eject the sd card, plug it in, start the RasPi up. If it doesn't boot *then*, try

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arm_freq = 800
gpu_freq = 300
sdram_freq = 450

Rinse and repeat.

If it doesn't boot then, let me know.

Matthew:out[/code]

Thanks for the tip, Matthew. I might try that later For now, I want to cope with the slowness of the thing by making Pred faster instead of the hardware. That'll benefit to all versions. I remember my very first build of Pred, on a P4, was running at 130 Kns... Two years later, on the same hardware, it was over 400 Kns (despite the eval was a bit more complex)

[JuLieN]

So, three months later, who here has bought a RasPi, and what are you doing with it?

As for me:
- I ported my chess engine (piece of cake)
- I'm learning ARM asm (useless (?) but funny)
- I'm getting more acquainted to Linux, as there's nothing else really usable on the RasPi (not that different from OSX, just less user friendly).

All in all, I'm very pleased with it, and for it's price there's no chance you can be wrong to buy one.

[ZirconiumX]

Only a moderator could resurrect the dead.

I bought another RasPi, and attempted to get a Beowulf cluster running. I hit the brick wall of there being no cluster-capable engines.

So nowadays, I occasionally pop into the Olympus ICS armed with a special version of Stockfish optimized for a RasPi - specifically the Leading Zero Count modification. (Marco still won't implement it)

Nowadays, a Raspberry Pi has turbo mode, which means you can get away with ridiculous things like run the Pi at 1GHz with my warranty intact.

My wishlist currently is to try and find a micro water cooling kit - because my heatsinks are practically useless in a sealed case.

Matthew:out

[bnemias]

...armed with a special version of Stockfish optimized for a RasPi - specifically the Leading Zero Count modification. (Marco still won't implement it)

I run Stockfish on a dockstar. It's been a long time since I optimized it, so perhaps I'm a little fuzzy. However I remember testing assembly versions of the bit functions using clz and comparing against the default implementation. I didn't see any measurable improvement in NPS and thus opted for the default bit operations.

I kind of want to try optimizing it again anyway using a newer gcc that other threads suggest are much improved. Is there a link to the modification you are talking about?

[jshriver]

I bought one a couple months back. So far I've tinkered with a couple open source programs, but mainly I use it to watch games on OICS on my TV via xboard.

24/7 computer chess channel on the tele

-Josh

[mephisto]

Julien
Introducing the SishFishPi dedicated chess computer project.
At the moment and still under development, the SishFishPi is a built using the Raspberry Pi Linux development board, the Teensy USB development board, Stockfish chess engine, and commodity of LCD/electronics. The SishFishPi integrates with a new software build for the "Sish" chess board. The end result, a small but very powerful chess machine. To be added over the next few months will be a new autosensory reed board to replace the push sensory ones we have at the moment plus LED's around the board to indicate the computers moves as well as them appearing on the LCD screen.
Hopefully by the end of the year we will have one to show you all.
Bryan

[Carotino]

Wikipedia entry: http://en.wikipedia.org/wiki/Raspberry_Pi

I'm sad to see that no real time clock chip is included. Apparently, a networked Raspberry Pi will have to query a time server as part of the boot sequence soon after a network interface is established. The alternative is to either manually set the date and time or run like it's January 1st, 1970.

Ubuntu is not included in the default set of supported operating systems. This is not too surprising as Ubuntu has gained a lot of bloat over the past few years.

I have been disappointed in recent Ubuntu versions. Maybe it's Linux itself but it's moving too far away from it's roots in my opinion. A lean and mean operating system for experts is what it has been, but their vision seems to be tto become the OS that even idiots can use. We already have Windows that even Grandma can check her email and browse the web and socially network.

Am I alone in feeling like this?

Suggestions for a different distribution for me to try? I'm not looking to be a linux guru or make problems for myself, but I just want the OS to get out of the way and stop trying to be the killer application.

Have you tried Kubuntu? The KDE interface is usually less avant garde than its Ubuntu sibling.

For an operating system that is fast, lightweight, and "gets out of your way" (to quote Don), I would recommend lubuntu or anything LXDE based. KDE is all about "nice" and graphical stuff that takes a lot of resources and aren't of much practical use...

Hard men use Salckware + BlackBox...

[j_romang]

So nowadays, I occasionally pop into the Olympus ICS armed with a special version of Stockfish optimized for a RasPi - specifically the Leading Zero Count modification. (Marco still won't implement it)

I submitted armv7 assembly to Marco, it is now included in Stockfish (https://github.com/mcostalba/Stockfish/ ... 03a3f31e56) ; but as the Rpi is armv6, I don't know if it has the 'rbit' assembly instruction ?
How did you implement your special version ?

[j_romang]

I just tested on my Rpi :

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{standard input}: Assembler messages:
{standard input}:1790: Error: selected processor does not support ARM mode `rbit r3,r3'

As expected, no rbit on armv6
So I'm really interested by your version

[ZirconiumX]

Basically - replacing msb() with

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Square msb(Bitboard b) {
  int h, l, m;
  assert (b != 0);
  __asm__("clz %0, %1" : "=r"(h) : "r"(b >> 32));
  __asm__("clz %0, %1" : "=r"(l) : "r"((uint32_t)(b)));
  m = ~((h - 32) >> 31); // ~0 (-1) if h >= 32, else 0
  return Square( (h+(m&l)) ^ 63);
}

means my crappy compile rivals Jim Ablett's.

I *did* see your ARMv7 patch, Jean.

No offence is intended - but in my opinion it is unneccessary due to the already 32-bit friendly Folded De Bruijin that SF has.

I have, however been thinking. Assuming that the LZCnt follows the dest, source pattern, then this could be used for quite a speedup on some systems (Stockfish becoming Cray-friendly perhaps?)

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#define USE_LZCNT
#define LZCNT "clz" // or cntlzw for PPC, or leadz for Cray, or lzcnt for AMD, etc.
...
#elif defined(USE_LZCNT)
Square msb(Bitboard b) {
  int h, l, m;
  assert (b != 0);
  __asm__(LZCNT " %0, %1" : "=r"(h) : "r"(b >> 32));
  __asm__(LZCNT " %0, %1" : "=r"(l) : "r"((uint32_t)(b)));
  m = ~((h - 32) >> 31); // ~0 (-1) if h >= 32, else 0
  return Square( (h+(m&l)) ^ 63);
}
#else
...

Maybe that would be platform-indepent enough for Marco's approval?

Matthew:out