Shortest time to complete a 2^67 trial factor (no factor) - Page 2

dsouza123 · 2003-08-21, 18:13

Wow, under 1 day 2^67 TF is already being done !

I thought it needed about a 3.6 GHz but the SSE2 instructions
on a P4 must be quite efficient.

A friend who is also doing TF is going to build a new machine
this may influence what chip/speed he gets.

I have been very curious about TF speeds and which CPU's are best,
but I don't have access to any PCs with SSE2.

All the posts have given really good information and insight.

Thanks

I wonder if the Opteron/Athlon64 will be this quick or if raw clock speed
will dominate ?

dsouza123 · 2003-08-21, 18:38

What are the facts on integer / FP x87 / int x87 / FP SSE2 / int SSE2 ?

I noticed the x87 has a 64 bit signed integer format and
the SSE2 has 64 and 128 integer support.

What is used at what levels ?

Does it start as 64 bit integer up to 2^62 using 2 32 bit registers ?
Switch to x87 then at 2^64 or 2^65 go to SSE2 if available ?
Is the SSE2 using integer or floating point ?

Would a Prime95 lite ( just the TF code, interface could remain the same )
be more efficient ? ( a much smaller exe that could remain in the cache )

Or is the code for TF small enough that the section that does the TF can stay in the cache L1, L2 ?

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2003-08-21, 18:13	#12
dsouza123 Sep 2002 662₁₀ Posts	Wow, under 1 day 2^67 TF is already being done ! I thought it needed about a 3.6 GHz but the SSE2 instructions on a P4 must be quite efficient. A friend who is also doing TF is going to build a new machine this may influence what chip/speed he gets. I have been very curious about TF speeds and which CPU's are best, but I don't have access to any PCs with SSE2. All the posts have given really good information and insight. Thanks I wonder if the Opteron/Athlon64 will be this quick or if raw clock speed will dominate ?

2003-08-21, 18:38	#13
dsouza123 Sep 2002 2·331 Posts	What are the facts on integer / FP x87 / int x87 / FP SSE2 / int SSE2 ? I noticed the x87 has a 64 bit signed integer format and the SSE2 has 64 and 128 integer support. What is used at what levels ? Does it start as 64 bit integer up to 2^62 using 2 32 bit registers ? Switch to x87 then at 2^64 or 2^65 go to SSE2 if available ? Is the SSE2 using integer or floating point ? Would a Prime95 lite ( just the TF code, interface could remain the same ) be more efficient ? ( a much smaller exe that could remain in the cache ) Or is the code for TF small enough that the section that does the TF can stay in the cache L1, L2 ?