Setting up an Ubuntu 10.10 miner - should I go 32 or 64 bit?

[jondecker76]

Hello

I just threw together an open-cooling miner from spare parts (I.e. everything screwed down to a piece of plywood), and will be starting out with one single ATI 5850 (though I  have 3 PCI-E slots, so I would like to eventually run 3 of these cards with extender cables to space things out and keep things cool)

All I need to do now is decide whether to go 32 or 64 bit version of Ubuntu 10.10 server edition - does anyone know if there is any kind of advantage to using the 64 bit distro?

Also, any suggestions on a decent miner that will (eventually) support 3 ATI 5850 cards working together?  I do plan on mining solo for now -  this looks like a fun hobby and I have no plans or aspirations of getting rich, plus I would love to start trading/spending bitcoins whenever possible, the concept really appeals to me!

thanks!

[eck]

Also, why 10.10 and not 11.04?

[error]

Also, why 10.10 and not 11.04?

Because 11.04 is a steaming pile of pig manure?

[eck]

why would that be? I've been using it and haven't had any issues, but if 10.10 is going to give me better performance or something, I'd rather go with that.

[laanwj]

unless you have a really ancient CPU go with 64

Indeed, or if you have very little memory (<2GB) it can also make sense to go with 32 bit. But that usually goes with ancient CPUs

[gat3way]

< 4GB However with PAE you can address more, up to 64GB. Over 8GB you will be suffering badly from the overhead of mapping/unmapping regions in lowmem. Anyway, it really does not matter. For a SSE2 CPU miner, going to 32bit on a 64-bit system would be detrimental as the number of xmm registers is cut by 2. With GPGPU stuff it does not matter.

[Inaba]

My mining boxes are all 1GB and 64 bit.  No real reason to put anything more in a mining box.

[laanwj]

< 4GB

Indeed, there are memory mapping tricks to get around it. But the main reason to use 32 bit for small memory machines is that 64 bit executables and data structures are a bit larger (pointers are two times as big).

[gat3way]

With 32-bit addressing you can address 4GB of physical memory, however there is 3:1 userspace:kernelspace mapping in linux, so a process can utilize up to 3GB of it. With PAE (aka bigmem) you can have up to 64GB addressable in linux, still you cannot escape the 3GB per-process limit. It does not concern mining though.

BTW it's interesting question whether a 32bit installation is more power-efficient than a 64-bit one. My uneducated guess would be that 32-bit one would be a bit more efficient just because of that what you mentioned: pointers being 4byte, not 8byte. The cacheline is the same, that would mean less memory transfers. However, I doubt there would be a big difference. However reality could prove me wrong. I guess it would be very beneficial if someone does the tests.