Dual CPU perfomance hit

[Paulie]

Originally Posted by lycorn

Paulie wrote:

I'm thinking of increasing it to ^67

That´s an interesting point. I assumed that the TF upper bound was, for a certain range of exponents, limited by the client, so for example in the 21M range we could only TF to 2^66. Regardless of being a good option or not (and I agree with garo that it´s not) how *could* we change the TF upper bound?

in the UNDOC.txt file, you can set the upper range. It also states that it's not recommended to be used with PrimeNet.

The reason I was thinking about it is since there is a performance hit doing dual LL's on an older P3 dual, since it's doing only factoring on one of the processors, I'd be willing to spend say 1/3 of the time of an LL trying to find a factor to save a future LL test.

I'm thinking from a project point of view vs. stats. Are DC's more useful to GIMPS or is finding factors during TF? :)

[smh]

I'd be willing to spend say 1/3 of the time of an LL trying to find a factor to save a future LL test.

But in the same time you can test one exponent from 66 to 67 bits you can do 2 from 59 to 66 bits, so in the same time you can TF 3 instead of 1 number with something like 15 times more chance of finding a factor.

Besides using factoroverride you can not use primenet.

The limits to which prime95 trail factors are carefully chosen. Maybe not optimal anymore due to changes in speed of the client. But optimal depts to trail factor differ on each processor

[garo]

Paulie,
From the project point of view don't touch a thing. The limits are carefully calculated and the amount of time you spend doing the extra bit of factoring will not translate to any savings for the project. It will REDUCE and not increase the overall project throughput.
Garo.

[Paulie]

Cool. Thanks everyone.

I think I'm going to change the lab server borg to be TF on both processors and find another P4 to borg for the DC's. I'll find more factors doing twice the work, but still get the DCs done.

It's a plan. :) :)

[Paulie]

Just to see what running two LL's would do:

Compaq DL380/G2, 1GB PC133 ECC, Dual 1.25Ghz P3's

DC = M8558603 iteration times

Proc1 DC = 0.089
Proc2 TF = a 20M exponent

Proc1 DC = 0.131
Proc2 DC = 0.132