Quote from: satoshi on June 25, 2010, 02:17:41
The 64-bit version shouldn’t be any faster than the 32-bit version, but it would be great if someone could do a side-by-side comparison of the two linux versions and check.  SHA-256 is a 32-bit algorithm and nothing in BitcoinMiner uses 64-bit at all.
But look here:

32-bit Linux version on Ubuntu 10.04

4 cores: 2500 khash/s
3 cores: 1900 khash/s
2 cores: 1260 khash/s
1 core: 630 khash/s

64-bit Linux version on Ubuntu 10.04 (new measure)

4 cores: 2880 khash/s
3 cores: 2150 khash/s
2 cores: 1450 khash/s
1 core: 720 khash/s

(Though I never created one coin, yet – but I don’t let bitcoin run on 4 cores the whole day, not even on 1 core…)

@Joozero – The Intel i7 860 is @ 2.8 Ghz, isn’t it? My Phenom II is @ 3 Ghz, that’s another important fact I think. I will try bitcoin on Windows 7 at the same machine later.

/edit

32-bit Win version on Windows 7 64-bit

4 cores: 2310 khash/s
3 cores: 1740 khash/s
2 cores: 1160 khash/s
1 core: 580 khash/s

Thanks virtualcoin, that’s a perfect comparison.

The 8% speedup from 32-bit Windows (2310k) to 32-bit Linux (2500k) is probably from the newer version of GCC on Linux (4.4.3 vs 3.4.5).

The 15% speedup from 32-bit to 64-bit Linux is more of a mystery.  The code is completely 32-bit.

Hmm, I think the 8 extra registers added by x86-64 must be what’s helping.  That would make a significant difference to SHA if it could hold most of the 16 state variables in registers.

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