ECM Takes far longer than estimated time
 

I set one of my cores to ECM work, just to see what it would do, and have noticed a repeatable discrpency. The thing that grabbed by attention was several exponents with -2 and -1 days remaining in my assignment list.

I have ECM work automatically assigned by Prime 95, which sets an estimated 2:50 (h:mm) time between completions. Actual completion time is about 5:05 between trials (3 curves of 5M candidates). Other type work is much more accurately predicted (as long as I'm not playing Starcraft 2).

I've checked everything I can think of to explain this significant slowdown. I have 3 GB assigned to memory. I've let the machine run solely Prime 95 for 2 days, just to get clean data.

The time discrepancy exists both on v. 25.11 and 26.3b3 (both the estimated time and actual completion time are about 10% lower under 26.3, but the relative ratio is roughly constant).

System:
i7-920 @ 3.71 GHz 6 GB RAM @ 1062 MHz Win 7 64-bit home premium

I double checked my older Athlon 64 x2 4200+ system. Estimated times are separated by 9:30, actual completion times are 13:30 apart. (Stock speed, only 4 GB @ PC3200 on this system ) Windows XP 32-bit, Prime 95 v26.2

Is this something I've done or configured, or are ECM completion estimates consistently 40% lower than actual times for most people?

I'd like to hear if other users see the same thing.

I'm inclined to believe this is just an error in my attempt at estimating ECM costs. I've a lot more experience with LL timings.

One question: How much time are you spending in stage 1 and stage 2? My only concern is thrashing during stage 2 due to lack of RAM.

Same here.....
 

I reported this about a couple years ago and at the time the suggestion was that ECM was lower credits because it is less significant in the search for primes....I'll see if I can find that thread.

Found one: [url]http://www.mersenneforum.org/showpost.php?p=169503&postcount=9[/url]

...in the meantime.

I had several different PCs doing ECM in the fall / winter of 2008. I did NOT have immediate access to all of them but the few I did the results were quite consistent:
- The actual completion time was close to double the original estimate
- The GhzDays per day for each PC was about half of what they produced with TF of LL/DC.

Again as we speak I have a PIV 3.4 Ghz doing ECM also in the 5M range.
The estimates were about 5.5 hours while the actual times were about 13 hours. Unlike P-1, Stage 2 ECM is actually a little faster than Stage 1.

This PC will output 2 GhzDays per day in any other work type but drops to about 1 per day with ECM (Fermat too).

If there is some good news: when I upgraded to 26.2 the actual times dropped to 11 hours ... about 15% faster.

P.S. On this same machine also after the upgrade P-1 was only about 5% faster even though I would have though it was the same basic code.

Prime95 26.2 estimates about 55 minutes, while completion is about 1:55. No disk thrashing (W7x64 reports >400MB available during stage 2).

[CODE]1808977 NF-ECM 2010-10-18 05:33 0.3 3 curves, B1=50000, B2=5000000 0.154
1808969 NF-ECM 2010-10-18 03:39 0.2 3 curves, B1=50000, B2=5000000 0.1546[/CODE]

Do you find the estimate to be off by a factor of 2 for exponents below 1 million? For B1 = 250000 too?

Lets find out:
M823051 B1=50000 gives an ETA of around 16.75 hrs (150 curves).
M1809209 B1=250000 gives ETA of around 3.25 hrs (3 curves).

ECM is not my thing ( I haven't examined the relationships between the bounds, exponent size and number of curves), so if you wanted the <1MM exponent with B1=250000, let me know.

Stage 2 is 60% of Stage 1
 

I looked over the last sets of ECM data in my worker window and found a consistent pattern. Stage 1 takes 60 minutes, Stage 2 takes 34 minutes.

This is on ECMs in the 5M range.

If I were going solely for maximum GHz-day credits, I'd stick with LL under 26.x, which brings in roughly 4.6 GHz-day/day. (it used to be < 4 under 25.11). My second choice being TF which nets me about 4.3 GHz-day credits per core compared to ECM's 2.7. I think ECM-F comes in even lower, but I don't have enough data to accurately estimate that.

My personal goal is to see if I can reach the 90% mark in all categories and get all sorts of colors in my status pie chart. I needed some excuse to OC my i7, after all.

[CODE]
[Oct 18 08:08] ECM on M5346227: curve #2 with s=3959854856274645, B1=50000, B2=5000000
[Oct 18 08:19] M5346227 curve 2 stage 1 at prime 9241 [18.48%]. Time: 668957.08 ms.
[Oct 18 08:31] M5346227 curve 2 stage 1 at prime 18587 [37.17%]. Time: 686872.08 ms.
[Oct 18 08:42] M5346227 curve 2 stage 1 at prime 27997 [55.99%]. Time: 667264.33 ms.
[Oct 18 08:53] M5346227 curve 2 stage 1 at prime 37313 [74.62%]. Time: 667994.29 ms.
[Oct 18 09:04] M5346227 curve 2 stage 1 at prime 46687 [93.37%]. Time: 665848.92 ms.
[Oct 18 09:08] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 237661.41 ms.
[Oct 18 09:08] Using 1435MB of memory in stage 2.
[Oct 18 09:08] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26272.08 ms.
[Oct 18 09:21] M5346227 curve 2 stage 2 at prime 1810213 [35.55%]. Time: 730060.37 ms.
[Oct 18 09:33] M5346227 curve 2 stage 2 at prime 3678377 [73.30%]. Time: 735423.91 ms.
[Oct 18 09:41] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 487886.31 ms.
[Oct 18 09:41] Stage 2 GCD complete. Time: 4047.01 ms.
[Oct 18 09:41] ECM on M5346227: curve #3 with s=4630087126100238, B1=50000, B2=5000000
[Oct 18 09:52] M5346227 curve 3 stage 1 at prime 9241 [18.48%]. Time: 668169.93 ms.
[Oct 18 10:03] M5346227 curve 3 stage 1 at prime 18587 [37.17%]. Time: 668837.56 ms.
[Oct 18 10:14] M5346227 curve 3 stage 1 at prime 27997 [55.99%]. Time: 666613.52 ms.
[Oct 18 10:26] M5346227 curve 3 stage 1 at prime 37313 [74.62%]. Time: 668173.77 ms.
[Oct 18 10:37] M5346227 curve 3 stage 1 at prime 46687 [93.37%]. Time: 675533.52 ms.
[Oct 18 10:41] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 237770.38 ms.
[Oct 18 10:41] Using 1435MB of memory in stage 2.
[Oct 18 10:41] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26124.28 ms.
[Oct 18 10:53] M5346227 curve 3 stage 2 at prime 1810213 [35.55%]. Time: 734652.72 ms.
[Oct 18 11:06] M5346227 curve 3 stage 2 at prime 3678377 [73.30%]. Time: 740824.76 ms.
[Oct 18 11:14] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 498160.99 ms.
[Oct 18 11:14] Stage 2 GCD complete. Time: 4235.70 ms.
[Oct 18 11:14] M5346227 completed 3 ECM curves, B1=50000, B2=5000000, We4: 8A28C044
[Oct 18 11:14] Using Core2 type-3 FFT length 288K, Pass1=384, Pass2=768
[Oct 18 11:14] ECM on M5346307: curve #1 with s=6577352004968829, B1=50000, B2=5000000
[Oct 18 11:25] M5346307 curve 1 stage 1 at prime 9257 [18.51%]. Time: 676291.25 ms.
[Oct 18 11:37] M5346307 curve 1 stage 1 at prime 18593 [37.18%]. Time: 679936.53 ms.
[Oct 18 11:48] M5346307 curve 1 stage 1 at prime 28001 [56.00%]. Time: 666833.96 ms.
[Oct 18 11:59] M5346307 curve 1 stage 1 at prime 37321 [74.64%]. Time: 668202.71 ms.
[Oct 18 12:10] M5346307 curve 1 stage 1 at prime 46691 [93.38%]. Time: 666216.70 ms.
[Oct 18 12:14] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 237611.44 ms.
[Oct 18 12:14] Using 1435MB of memory in stage 2.
[Oct 18 12:15] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 25614.31 ms.
[Oct 18 12:27] M5346307 curve 1 stage 2 at prime 1810213 [35.55%]. Time: 730033.41 ms.
[Oct 18 12:39] M5346307 curve 1 stage 2 at prime 3678377 [73.30%]. Time: 741758.74 ms.
[Oct 18 12:47] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 487752.87 ms.
[Oct 18 12:47] Stage 2 GCD complete. Time: 4041.83 ms.
[Oct 18 12:47] ECM on M5346307: curve #2 with s=8744690854802613, B1=50000, B2=5000000
[Oct 18 12:58] M5346307 curve 2 stage 1 at prime 9241 [18.48%]. Time: 669026.74 ms.
[Oct 18 13:10] M5346307 curve 2 stage 1 at prime 18587 [37.17%]. Time: 667459.10 ms.
[Oct 18 13:21] M5346307 curve 2 stage 1 at prime 27997 [55.99%]. Time: 666842.28 ms.
[Oct 18 13:32] M5346307 curve 2 stage 1 at prime 37313 [74.62%]. Time: 667675.53 ms.
[Oct 18 13:43] M5346307 curve 2 stage 1 at prime 46687 [93.37%]. Time: 665764.93 ms.
[Oct 18 13:47] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 238434.54 ms.
[Oct 18 13:47] Using 1435MB of memory in stage 2.
[Oct 18 13:47] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26260.59 ms.
[Oct 18 14:00] M5346307 curve 2 stage 2 at prime 1810213 [35.55%]. Time: 732289.21 ms.
[Oct 18 14:12] M5346307 curve 2 stage 2 at prime 3678377 [73.30%]. Time: 737348.08 ms.
[Oct 18 14:20] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 491219.40 ms.
[Oct 18 14:20] Stage 2 GCD complete. Time: 4235.47 ms.
[Oct 18 14:20] ECM on M5346307: curve #3 with s=6305224986021923, B1=50000, B2=5000000
[Oct 18 14:31] M5346307 curve 3 stage 1 at prime 9241 [18.48%]. Time: 667893.83 ms.
[Oct 18 14:42] M5346307 curve 3 stage 1 at prime 18587 [37.17%]. Time: 675206.04 ms.
[Oct 18 14:54] M5346307 curve 3 stage 1 at prime 27997 [55.99%]. Time: 667115.13 ms.
[Oct 18 15:05] M5346307 curve 3 stage 1 at prime 37313 [74.62%]. Time: 667153.30 ms.
[Oct 18 15:16] M5346307 curve 3 stage 1 at prime 46687 [93.37%]. Time: 666043.84 ms.
[Oct 18 15:20] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 237737.22 ms.
[Oct 18 15:20] Using 1435MB of memory in stage 2.
[Oct 18 15:20] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26175.70 ms.
[Oct 18 15:32] M5346307 curve 3 stage 2 at prime 1810213 [35.55%]. Time: 732643.81 ms.
[Oct 18 15:45] M5346307 curve 3 stage 2 at prime 3678377 [73.30%]. Time: 737581.26 ms.
[Oct 18 15:53] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 489887.84 ms.
[Oct 18 15:53] Stage 2 GCD complete. Time: 4241.84 ms.
[Oct 18 15:53] M5346307 completed 3 ECM curves, B1=50000, B2=5000000, We4: 8A15C040
[Oct 18 15:53] Using Core2 type-3 FFT length 288K, Pass1=384, Pass2=768
[Oct 18 15:53] ECM on M5346317: curve #1 with s=6536885047291095, B1=50000, B2=5000000
[Oct 18 16:04] M5346317 curve 1 stage 1 at prime 9257 [18.51%]. Time: 670165.62 ms.
[Oct 18 16:15] M5346317 curve 1 stage 1 at prime 18593 [37.18%]. Time: 667559.79 ms.
[Oct 18 16:26] M5346317 curve 1 stage 1 at prime 28001 [56.00%]. Time: 666960.05 ms.
[Oct 18 16:38] M5346317 curve 1 stage 1 at prime 37321 [74.64%]. Time: 667745.78 ms.
[Oct 18 16:49] M5346317 curve 1 stage 1 at prime 46691 [93.38%]. Time: 674392.78 ms.
[Oct 18 16:53] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 237330.25 ms.
[Oct 18 16:53] Using 1435MB of memory in stage 2.
[Oct 18 16:53] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26211.91 ms.
[Oct 18 17:05] M5346317 curve 1 stage 2 at prime 1810213 [35.55%]. Time: 733536.68 ms.
[Oct 18 17:18] M5346317 curve 1 stage 2 at prime 3678377 [73.30%]. Time: 736486.30 ms.
[Oct 18 17:26] Stage 2 complete. 641527 transforms, 14 modular inverses. Time: 490900.45 ms.
[Oct 18 17:26] Stage 2 GCD complete. Time: 4247.59 ms.
[Oct 18 17:26] ECM on M5346317: curve #2 with s=2306703053935178, B1=50000, B2=5000000
[Oct 18 17:37] M5346317 curve 2 stage 1 at prime 9241 [18.48%]. Time: 669569.10 ms.
[Oct 18 17:48] M5346317 curve 2 stage 1 at prime 18587 [37.17%]. Time: 669012.09 ms.
[Oct 18 17:59] M5346317 curve 2 stage 1 at prime 27997 [55.99%]. Time: 667672.69 ms.
[Oct 18 18:11] M5346317 curve 2 stage 1 at prime 37313 [74.62%]. Time: 668901.21 ms.
[Oct 18 18:22] M5346317 curve 2 stage 1 at prime 46687 [93.37%]. Time: 666734.86 ms.
[Oct 18 18:26] Stage 1 complete. 1286025 transforms, 1 modular inverses. Time: 238727.96 ms.
[Oct 18 18:26] Using 1435MB of memory in stage 2.
[Oct 18 18:26] Stage 2 init complete. 7129 transforms, 1 modular inverses. Time: 26065.16 ms.
[Oct 18 18:38] M5346317 curve 2 stage 2 at prime 1810213 [35.55%]. Time: 732045.98 ms.
[Oct 18 18:51] M5346317 curve 2 stage 2 at prime 3678377 [73.30%]. Time: 747303.87 ms.
[Oct 18 18:59] Stage 2 complete. 641525 transforms, 14 modular inverses. Time: 490230.41 ms.
[Oct 18 18:59] Stage 2 GCD complete. Time: 4248.69 ms.
[Oct 18 18:59] ECM on M5346317: curve #3 with s=1762390611020433, B1=50000, B2=5000000
[Oct 18 19:10] M5346317 curve 3 stage 1 at prime 9241 [18.48%]. Time: 667292.30 ms.
[Oct 18 19:21] M5346317 curve 3 stage 1 at prime 18587 [37.17%]. Time: 635002.78 ms.
[Oct 18 19:31] M5346317 curve 3 stage 1 at prime 27997 [55.99%]. Time: 635107.50 ms.
[/CODE]

[QUOTE=sdbardwick;233766]Lets find out:
M823051 B1=50000 gives an ETA of around 16.75 hrs (150 curves).
M1809209 B1=250000 gives ETA of around 3.25 hrs (3 curves).[/QUOTE]
M1809209 B1=250000 actual time to completion was just under 7 hours, so the ETA x2 holds true. M823051 just started, so I'll give an estimated actual completion time when some data is available.

[QUOTE=sdbardwick;233766]Lets find out:
M823051 B1=50000 gives an ETA of around 16.75 hrs (150 curves).
M1809209 B1=250000 gives ETA of around 3.25 hrs (3 curves).[/QUOTE]

[QUOTE=sdbardwick;233818]M1809209 B1=250000 actual time to completion was just under 7 hours, so the ETA x2 holds true. M823051 just started, so I'll give an estimated actual completion time when some data is available.[/QUOTE]
M823051 completed 150 curves in 37 hours, so again more than 2x the estimated time.

Both were tested with 26.2B1, W7x64, Phenom2 940@stock (3.06 GHz) with DDR2-800, 640MB/640MB day/night memory setting.

Question for y'all:

Is "hours per day" set at 24?
What is your rolling average?
Do you get better estimates if you reset your rolling average back to 1000?
@sdbardwick: Do you think you are getting shortchanged on PrimeNet credit?

On my Mac running Windows Vista 32-bit, I am getting good estimates for M510331, B1 = 50000.

My one curve on a 2.5GHz machine took 585 sec. 585/86400*2.5 = 0.0169 GHzD expected credit. Actual credit was 0.0139 GHzD. Not wildly off.

Hours per day = 24
Rolling Average = 1032

8.93hrs to complete 3 curves (stage 1 and stage 2) of M5356357 with 1524MB/1524MB RAM setting.

(8.93*60*60)/(24*60*60)*3.2=
32556/86400 * 3.2 = 1.19467 GHz-days anticipated
[CODE]Sending result to server: UID: xxxxxxx/PH2x6-1090T, M5356357 completed 3 ECM curves, B1=50000, B2=5000000, We4: 8ADFC1A7, AID: AF7578AE94B8222E53CDAEE5D73022C9

PrimeNet success code with additional info:
CPU credit is 0.5051 GHz-days.[/CODE]
Random thought: Is it possible that only one stage is being credited and/or being used to calculate ETA?
Estimated time is 4:20; actual time is still about double.

OK. I'm seeing similar behavior ECMing M5000000. I'm not seeing it for M500000. This leads me to believe the estimates go bad when ECM data exceeds my 6MB L2 cache.

I'll investigate some more by profiling.

Here's the deal:

ECM has two possible stage 2 implementations.

The first does 2 FFTs (the same cost as one squaring) and one addition per stage 2 prime. It also does some modular inverses (the same cost as a GCD) and some muls and adds based on the number of temporaries that can be allocated.

The second implementation does 4 FFTs and two additions per stage 2 prime.


For small ECM numbers, Prime95 does a fairly good job of estimating the time. It is probably off by ~10% in both stage 1 and 2 because it is only considering the cost of the FFTs -- and the additions aren't free. A large number of temps can be allocated, meaning we don't do many GCDs, and they don't cost much anyway.

As numbers get larger, fewer temporaries can be allocated and GCDs get more costly. Consequently, stage 2 approaches twice as long as expected. Furthermore, cache miss penalties get larger (you need triple the prefetch bandwidth to do a multiply with 2 sources and 1 destination as opposed to an LL test which does a squaring where the source and destination are the same). The extra stage 1 and 2 overhead is more like 20%.

Finally, as numbers get very large Prime95 switches to the 4 FFT stage 2 which costs exactly double what Prime95 is estimating.

The amount of memory you let prime95 use, your CPUs cache sizes and miss penalties make an exact formula near impossible. And for the Primenet server it is impossible as it doesn't have near enough information available.

So, I'm considering something along these lines. For exponents below say 100,000 add a 10% overhead to the time estimate and Primenet credit. Between 100,000 and say 5,000,000 I'll linearly increase the overhead from 10% to 20% and linearly increase the stage 2 estimate from 1x to 2x. It isn't perfect, but it would be better.

For example, exponents >= 5M currently get 13 "units of credit" in stage 1 and 6 in stage 2. This would increase to (13+12)*1.2. In other words, increase from 19 to 30.

Looks like a rational solution to me. Thanks for taking the time to suss it out.

Thank you
 

[QUOTE=Prime95;234588]Here's the deal:
....[/QUOTE]

Your explanation makes sense.

I had been doing some OCing and benchmarking with LL and noticed a signficant (4%) increase in iteration time between 2 and 3 LL tasks running simultaneously. Dropping to 1 core improved my iteration time slightly, but not by much (1%). I figured the various threads were fighting over a common resource (memory or L3 cache).

I was about to repeat the benchmarking using ECM tests to see if they too were fighing over memory, but didn't get around to it before you posted. All my previous posts were referring to a PC with saturated cores (1 ECM + x LL) on my K8 dual core and i7 quad.

On with the bug search!

[QUOTE=Prime95;234588]Here's the deal:
So, I'm considering something along these lines. For exponents below say 100,000 add a 10% overhead to the time estimate and Primenet credit. Between 100,000 and say 5,000,000 I'll linearly increase the overhead from 10% to 20% and linearly increase the stage 2 estimate from 1x to 2x. It isn't perfect, but it would be better.

For example, exponents >= 5M currently get 13 "units of credit" in stage 1 and 6 in stage 2. This would increase to (13+12)*1.2. In other words, increase from 19 to 30.[/QUOTE]

Sounds great....I would have been doing more ECM instead of TF on lower exponents except for this issues of estimates being twice as long and credits being half as much. And I will assume I'm not the only one?

Just let me know when or what version I need to upgrade to.

Thanks

The server is now handing out the enhanced ECM cpu credit.
Past ECM credit has been bumped about 20%.

Cool! Thanks!

[QUOTE=Prime95;235762]The server is now handing out the enhanced ECM cpu credit.
Past ECM credit has been bumped about 20%.[/QUOTE]

Old .... Rank [SIZE=1]30[/SIZE][SIZE=1]/425[/SIZE] GHzd[SIZE=1] 240.4511 [/SIZE]Count[SIZE=1] 644
[/SIZE]New ... Rank [SIZE=1]41[/SIZE][SIZE=1]/425[/SIZE] GHzd[SIZE=1] 283.8886 [/SIZE]Count[SIZE=1] 644[/SIZE]
[SIZE=1]
[/SIZE]How come I'm not exactly satisfied? :unsure:

[QUOTE=Prime95;235762]The server is now handing out the enhanced ECM cpu credit.
Past ECM credit has been bumped about 20%.[/QUOTE]

Oh, so close to perfect timing ... I just started a core on ECM; it just finished exactly one assignment before the new values came in.

To compare:
New: 5277187 NF-ECM 2010-11-06 05:24 45.0 3 curves, B1=50000, B2=5000000 0.7204
Old: 5277169 NF-ECM 2010-11-05 17:52 44.5 3 curves, B1=50000, B2=5000000 0.4501

Note: credit went from .4501 to .7204 (60% more in this case)

Seems reasonable to me.
Thanks

[QUOTE=ckdo;235772]Old .... Rank [SIZE=1]30[/SIZE][SIZE=1]/425[/SIZE] GHzd[SIZE=1] 240.4511 [/SIZE]Count[SIZE=1] 644
[/SIZE]New ... Rank [SIZE=1]41[/SIZE][SIZE=1]/425[/SIZE] GHzd[SIZE=1] 283.8886 [/SIZE]Count[SIZE=1] 644[/SIZE]
[SIZE=1]
[/SIZE]How come I'm not exactly satisfied? :unsure:[/QUOTE]

[code]
Pre-2009 651000 1.1813
1/1/9 – 4/1/9 1103000 1.2506
4/1/9-7/1/9 632344 1.1785
7/1/9-10/1/9 734200 1.1939
10/1/9-1/1/10 733926 1.1939
1/1/10-4/1/10 746563 1.1958
4/1/10-7/1/10 843000 1.2105
7/1/10-10/1/10 999628 1.2346
10/1/10-pres. 909239 1.2207
[/code]

The above table shows the average ECM exponent tested in each time period and the corresponding CPU credit multiplier. Your ECM results must have been reported during a quarter with a smaller average exponent.

Significantly less important, but maybe the following belongs in this thread:

The PRP estimated times are about a half of what it really takes; for example, try:
[FONT=Arial Narrow][Worker #1][/FONT]
[FONT=Arial Narrow]PRP=2,10,249448,1,0,0,"3"[/FONT]
[FONT=Arial Narrow]PRP=2,10,249447,1,0,0,"3"[/FONT]
[FONT=Arial Narrow]PRP=2,10,249442,1,0,0,"3"[/FONT]
[FONT=Arial Narrow]PRP=2,10,249435,1,0,0,"3"[/FONT]
[FONT=Arial Narrow]PRP=2,10,249431,1,0,0,"3"[/FONT]

It takes about 7 minutes on a particular computer, while the Status page "promises" ~3.5 minutes:
[ATTACH]5879[/ATTACH]

[QUOTE=Batalov;235816]The PRP estimated times are about a half of what it really takes; for example, try:
[FONT=Arial Narrow]PRP=2,10,249448,1,0,0,"3"[/FONT][/QUOTE]

Bug in the code. Estimate is off by log2(10).

Right, sound about right.
I re-observed the running times and they are about 9-10minutes (the next FFT size kicked in), so 1:0.3 is right.

[QUOTE=Prime95;235762]The server is now handing out the enhanced ECM cpu credit.
Past ECM credit has been bumped about 20%.[/QUOTE]

Do you plan to also adjust the code that estimates the completion times? For me it is still out by about a factor of 2. I am completing the assignments in 11.5 hours but the estimate is 5.5 hours

Closer here
 

[QUOTE=petrw1;235887]Do you plan to also adjust the code that estimates the completion times? For me it is still out by about a factor of 2. I am completing the assignments in 11.5 hours but the estimate is 5.5 hours[/QUOTE]

Under 26.3b3 (64-bit) the estimates for ECM work in the 5.4M range are about 3:05 apart in my assignments. Actual time is ~ 4:00. That's closer than I used to see at least.

The GHz-day credits now match roughly what I see from LL or TF work (~ 4.25 GHz-days per 3.8GHz i7 core), so that change was well done.

ECM oddity? Saving the clutter of a new thread.
 

Just for fun I decided to complete the ECM of 355717; the lowest exponent that was not "DONE" ECM at B1=50,000, B2=5,000,000.

I ran 114 curves (took my PIV only 18 hours). :boxer:
Sorry, no factor found. :sad:

I checked the ECM Progress page about an hour after the test finished and sure enough it shows "DONE" in the first column

BUT it also shows 56 curves in column 2 though no such activity shows up in the Exponent Status report. :confused:

[QUOTE=petrw1;237626]BUT it also shows 56 curves in column 2 though no such activity shows up in the Exponent Status report. :confused:[/QUOTE]

This is normal (and confusing). The column header shows the number of curves that need to be run at that B1 level [I]if you are starting from scratch[/I]. However, we aren't starting from scratch. We've already run 300ish curves at B1=50000, which is equivalent to having run 56 curves at B1=250000.

I took the remaining exponents in the 35x,xxx range and completed the first level of ECM for them (B1/B1=50,000/5,000,000)

In most cases I took the count from about 180 to 280.
80 exponents
~7,700 curves in total
4 factors found.

[QUOTE=petrw1;251263]I took the remaining exponents in the 35x,xxx range and completed the first level of ECM for them (B1/B1=50,000/5,000,000)

In most cases I took the count from about 180 to 280.
80 exponents
~7,700 curves in total
4 factors found.[/QUOTE]
Roughly how many GHz-days, and how long did it take you?

[QUOTE=KingKurly;251267]Roughly how many GHz-days, and how long did it take you?[/QUOTE]

80.6 Ghz days total (0.5239 for each 50 curves)
PIV 2.8 GHZ completed 50 curves in just under 10 hours
PIV 3.4 GHZ completed 50 curves in just under 8 hours

[QUOTE=Prime95;234588]For exponents below say 100,000 add a 10% overhead to the time estimate and Primenet credit. Between 100,000 and say 5,000,000 I'll linearly increase the overhead from 10% to 20%[/QUOTE]For what it's worth, I've now included these modifications in my [url=http://mersenne-aries.sili.net/credit.php]credit calculator[/url].