20080425, 07:39  #1 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
2^{5}×283 Posts 
PSI, mpg, GHz P4days and P90 years
I now that pounds per square inch are related to atmospheric pressure, something like 15psi, right?
Miles per gallon is another ludicrous monster... apparently can be related to liters per 100km, but I care much more about what is a GHz P4days in P90 years (which are as most of you know, forever)? I did f'ing google! 
20080511, 01:13  #2 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
2^{5}·283 Posts 
I'll answer it myself, then.
1 P90year = 6.085 GHz P4days 0.16434 P90years = 1 GHz P4day Established empirically (by observing credits for similar jobs on V4 and V5 servers) Last fiddled with by Batalov on 20080511 at 01:18 
20080511, 01:46  #3 
P90 years forever!
Aug 2002
Yeehaw, FL
2×5×691 Posts 
my calcs
// In Primenet v4 we used a 90 MHz Pentium CPU as the benchmark machine
// for calculating CPU credit. The official unit of measure became the // P90 CPU year. In 2007, not many people own a plain Pentium CPU, so we // adopted a new benchmark machine  a single core of a 2.4 GHz Core 2 Duo. // Our official unit of measure became the C2GHD (Core 2 GHz Day). That is, // the amount of work produced by the single core of a hypothetical // 1 GHz Core 2 Duo machine. A 2.4 GHz should be able to produce 4.8 C2GHD // per day. // // To compare P90 CPU years to C2GHDs, we need to factor in both the // the raw speed improvements of modern chips and the architectural // improvements of modern chips. Examining prime95 version 24.14 benchmarks // for 640K to 2048K FFTs from a P100, PII400, P42000, and a C2D2400 // and compensating for speed differences, we get the following architectural // multipliers: // // One core of a C2D = 1.68 P4. // A P4 = 3.44 PIIs // A PII = 1.12 Pentium // // Thus, a P90 CPU year = 365 days * 1 C2GHD * // (90MHz / 1000MHz) / 1.68 / 3.44 / 1.12 // = 5.075 C2GHDs 
20080511, 16:29  #4  
"Richard B. Woods"
Aug 2002
Wisconsin USA
2^{2}×3×641 Posts 
Quote:
If GIMPS had adopted my suggested PCindependent standard a few years ago, you wouldn't be at the mercy of techology's forcing you to do all that repeatedly. We'd already have a workunit that can stand the test of time. For which we could be thankful each and every succeeding year.     Hey, how come a forum search for turkey or microwave doesn't find a certain thread from a few years ago, like it used to? Last fiddled with by cheesehead on 20080511 at 16:40 Reason: Corrected spelling of the plural of gramturkey. 

20080511, 19:10  #5 
"Lucan"
Dec 2006
England
2×3×13×83 Posts 
Having recently been reminded that a US gallon
differs from a UK one, I am still pondering whether this makes petrol more or less expensive here. BTW what was your PCindependent standard? Last fiddled with by davieddy on 20080511 at 19:14 
20080512, 19:55  #6  
1976 Toyota Corona years forever!
"Wayne"
Nov 2006
Saskatchewan, Canada
10DB_{16} Posts 
Quote:
As long as we continue to base it on the CPU of the day are we not setting ourselves up for another needed adjustment in another few years? Would not something more generic like GFLOPS be more time persistent? Just my 2 cents (1.9 Canadian Pennies) worth. 

20080512, 22:57  #7 
Einyen
Dec 2003
Denmark
2×3×5^{2}×19 Posts 
From v4 server stats:
Test Type CPU yr/day GFLOP/s    LucasLehmer 2527.820 30429.135 You can calculate how many GFlop 1 P90 cpu year is: 30429.135 GFLOP/s * 86400 s/day / 2527.820 CPUyr/day = 1,040,057 GFLOP/CPUyr(P90) This calculator on Team Prime Rib can calculate how many P90 yrs per LL test, but I'm curious what the formula is. Its based on FFT size: http://www.teamprimerib.com/rr1/bin/calc_p90.php Last fiddled with by ATH on 20080512 at 22:59 
20080513, 05:10  #8 
Sep 2006
Brussels, Belgium
2^{2}·383 Posts 

20080513, 08:30  #9 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
2^{5}·283 Posts 
that formula is old?
From that thread
I wonder if thе 39,500,000 limit (where 2560K FFT kicks in) is used now instead of 40,250,000 in the formula on the server. If it isn't, it may be unfair to the people doing the numbers between these bounds  they receive 25% less credit than they did work (they almost inevitably use 2560K FFT, not 2048K). All other limits are shifted, similarly. 
20080513, 12:08  #10 
"Serge"
Mar 2008
Phi(3,3^1118781+1)/3
2^{5}·283 Posts 
Here's an example that one cannot rely on anything historically "axiomatic" (USD vs CAD)  these days, not only USD is lower than a euro,  it is ridiculously lower. Now it is lower than CAD and australlian dollar, too... and the yen is next... Well, maybe first the rouble, then the yen.
Just my 0.02 yen. 
20080513, 17:18  #11  
Sep 2006
Brussels, Belgium
2^{2}×383 Posts 
Quote:
Some of the parameters will change with the V5 server. Jacob 

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