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-   -   5*2^n-1 Reservation Thread (https://www.mersenneforum.org/showthread.php?t=9472)

PatrickSchmeer 2007-10-17 11:06

500-525 complete - no primes found.
Results file sent to Curtis.
Just started at n=550000.
Reserving the next available range.

Patrick

gd_barnes 2007-10-18 20:20

LLRing and sieving ETA's
 
Curtis,

I started LLRing 630-665 and sieving 665-4M for 53T-58T late last night. ETA on the LLR is about 6 days (10/24) on 2 cores. BIG BIG jump in the timings after the fftlen increase at n=633.3K...from 500 secs. to 700 secs.! :sad: Ouch! (now at n=634K)

I think somebody has it in for me to give me the ranges where the timings make a big jump. :smile:

ETA on the P=53T-58T sieve range is 10/28 per sr1sieve on 2 cores on my 1.6Ghz Athlon. Tonight I'll remove the ranges you suggested in your PM.

Since we're reserving right after starting a new range, I'll reserve the next available range after Carlos' and Patrick's recent requests. I'm thinking 700K-720K to Carlos, 720K-740K to Patrick, and 740K-760K for me. Timings are getting pretty intense at this level. I'm not used to this! :smile:


Gary

em99010pepe 2007-10-18 20:39

Gary,

I suppose the goal here is to reach 1M until the end of the year.....
Those 700 sec per test are for which core speed? Here's an example of the current time I get with one of the cores of the 2.4 GHz quad-core for the 5th RPS Drive at n=778k: 57*2^778993-1 689.756 sec.

Carlos

VBCurtis 2007-10-19 01:24

Gary- thanks for the timing report. I extrapolated from my 600k timing sample (550 sec on a P4-2750), which explains why I suddenly thought we were not under-sieving. If there really is a 30-40% jump in execution times at 633, the original sieve-depth estimates are still accurate (I wondered how I was so far off!). Nonetheless, removing the lower candidates is still likely wise.

If you were at 500 sec before the jump, I'm guessing you have a P4-3.2. Core2's LLR at roughly a P4 of 50-60% higher clock speed, so Carlos' 2.4 would get timings equivalent to P4-3.6 to 3.8, or 15-20% faster than Gary. That leaves some error in my estimates, since Carlos is under 700 sec at 775k on 57.... but I'm in the ballpark.

Gary and I are looking to sieve to 58T in the next 10 days, then release files from 700 to 840 or so. 700 to 760 are spoken for... get 'em while they're hot! One reservation at a time, from each batch, please. When we get sieving ahead of LLR reservations, we'll revert to the RPS-drive style of reserving the next range when the current range is about to finish.

Finally, there will be a large break at n=1.2M. Sheep's sieving farm is on hiatus at the moment, and we'll hit a wall at that point until he comes back online. In a perfect world, we'll hit 1M by 1/1/2008, 1.2M by 1 Mar, and Sheep will be back sieving before then. I'll hope.
-Curtis

gd_barnes 2007-10-19 05:25

More exact CPU specs and speeds
 
[quote=VBCurtis;116664]Gary- thanks for the timing report. I extrapolated from my 600k timing sample (550 sec on a P4-2750), which explains why I suddenly thought we were not under-sieving. If there really is a 30-40% jump in execution times at 633, the original sieve-depth estimates are still accurate (I wondered how I was so far off!). Nonetheless, removing the lower candidates is still likely wise.

If you were at 500 sec before the jump, I'm guessing you have a P4-3.2. Core2's LLR at roughly a P4 of 50-60% higher clock speed, so Carlos' 2.4 would get timings equivalent to P4-3.6 to 3.8, or 15-20% faster than Gary. That leaves some error in my estimates, since Carlos is under 700 sec at 775k on 57.... but I'm in the ballpark.

Gary and I are looking to sieve to 58T in the next 10 days, then release files from 700 to 840 or so. 700 to 760 are spoken for... get 'em while they're hot! One reservation at a time, from each batch, please. When we get sieving ahead of LLR reservations, we'll revert to the RPS-drive style of reserving the next range when the current range is about to finish.

Finally, there will be a large break at n=1.2M. Sheep's sieving farm is on hiatus at the moment, and we'll hit a wall at that point until he comes back online. In a perfect world, we'll hit 1M by 1/1/2008, 1.2M by 1 Mar, and Sheep will be back sieving before then. I'll hope.
-Curtis[/quote]


Thanks for that explanation Curtis. I'm really a little confused about computer types and speeds. (It used to be so easy to go by Mhz/Ghz CPU speed but things have changed a lot in the last 2-3 years.) You were close on the machine type. I'm using one of my three Dell core-2 duos and it is only slightly slower than my single-core 3.2-Ghz P4 desktop that I use as my main personal machine. So I assumed it was a 3.0 Ghz or the equivalent. But it's actually 1.66 Ghz, which I could never quite understand until your explanation here. Even though half the Ghz speed, each core is only about 10% slower than my main desktop running one core. Carlos, your 2.4-Ghz quad machine must be like if I had a 2.4-Ghz Dell core-2 duo (vs. my 1.6 Ghz), i.e. 50% Ghz-speed faster than what I'm running. Although I'm not sure if that translates to 50% faster LLR time, i.e. 1/3rd less or 600 vs. 400 secs as an example.

Curtis, the 500 to 700-second jump was a slight exaggeration but not much. It actually went from about 520 to 690. About a 33% jump. How does that make the sieving look now? So you'll know exactly what I'm running and will have a better estimate for sieving, here is a cut-and-paste right out of LLR for my Dell core-2 duo as well as exact timings before and after the fftlen increase:

(Dell core-duo CPU specs):
Intel(R) Core(TM) 2 CPU T5500 @ 1.666Ghz
CPU speed: 1662.38 MHz
CPU features: RDTSC, CMOV, PREFETCH, MMX, SSE, SSE2
L1 cache size: 32 KB
L2 cache size: 2048 KB

Timings:
5*2^633108-1 519.754 secs.
5*2^633140-1 519.544 secs.
*****
5*2^634922-1 691.318 secs.
5*2^635020-1 692.568 secs.


Here's something confusing...My main sieving machine is an Athlon dual-core laptop that also runs at 1.66 Ghz. But it LLR's at half of the speed of the Dell core-duos although it sieves at > 75% of the speed of them. So I always only use it for sieving. By the way, I'm only 'assuming' it is an Athlon based on the CPU specs for it from LLR as follows:

(Assumed Athlon CPU specs):
AMD Turion(tm) 64 X2 Mobile Technology TL-50
CPU speed: 1607.28 Mhz
CPU features: RDTSC, CMOV, PREFETCH, MMX, SSE, SSE2
L1 cache size: 64 KB
L2 cache size: 256 KB


Curtis, I will probably stop my LLR effort somewhere in the n=800's. There will be plenty of people to continue from there. This is mostly why I don't pick up ranges from the team efforts much. I have nothing against them at all but there's almost always plenty of people on them and the tests take too long for my tastes and I prefer to LLR large n-ranges at once. As you know, I try to find dormant k's that need to be worked and k's with gaps that need to be filled and k's that are 'behind the curve' in how far they should have been tested. k=5 certainly filled the 'behing the curve' case.

It will be a stretch for us to get LLR to n=1M by year-end with or without me after n=800's, but it can be done. If Carlos can keep throwing 2 or 3 cores of that new very speedy quad-core of his at the effort, we may just get there. Kosmaj or Karsten may even want to throw in a CPU or two at it. Mostly, I'm confident that all ranges up to n=1M will have LLRing 'in the works' by year end. It would be a very significant accomplishment if all LLR tests were done to n=1M because of the amount of time each candidate will take to LLR at that point.


Gary

BlisteringSheep 2007-10-19 07:55

Curtis - If you can carve out a non-essential sieve range (ie. something that's not in anyone's critical path if it takes a week to finish), I believe I can start scheduling some time on the farm now. It'll be a while before everything is back to full speed (a large chunk of it is still in boxes), but it should help some.
Sheep :alex:

em99010pepe 2007-10-19 08:19

Gary,

One core of the 2.4 GHz quad-core is 45% faster than one of your 1.66GHz core. I also have a T5500 and that's the difference I get. The T5500 is as fast as my work machine, a P4 631 3.0GHz.
So for LLRing I have for sure at least 5 cores and the possibility to fire up more 2 at home and 3 at work.

Carlos

VBCurtis 2007-10-19 08:41

Sheep- I plan to be at 75T by 15 Nov. Start at 75T, and any work you get done will be a bonus. I know sr1 isn't the easiest for you to run, so perhaps just run on a small handful of cores? I'll send the appropriate sieve file for sr1 presently.

After 15 Nov, I'll sieve at about 6T/week until catching the big sieve at 150T.

Gary- I have the identical Athlon laptop CPU, except for 64bit linux instead of windows (it also has Vista, which motivated me to adjust to linux on laptop). Your Core2s also appear to be laptop chips, so the LLR timings you get are surprisingly quick (due to memory speeds and other power-related issues, a laptop and desktop chip of same speed and type are not equal). I'll run some k=5 on the Core2-2850 and see how fast the timings are (I predict 350 seconds at 610k, but that would not be a scaling of your speed).
-Curtis

gd_barnes 2007-10-19 17:37

[quote=VBCurtis;116684]Sheep- I plan to be at 75T by 15 Nov. Start at 75T, and any work you get done will be a bonus. I know sr1 isn't the easiest for you to run, so perhaps just run on a small handful of cores? I'll send the appropriate sieve file for sr1 presently.

After 15 Nov, I'll sieve at about 6T/week until catching the big sieve at 150T.

Gary- I have the identical Athlon laptop CPU, except for 64bit linux instead of windows (it also has Vista, which motivated me to adjust to linux on laptop). Your Core2s also appear to be laptop chips, so the LLR timings you get are surprisingly quick (due to memory speeds and other power-related issues, a laptop and desktop chip of same speed and type are not equal). I'll run some k=5 on the Core2-2850 and see how fast the timings are (I predict 350 seconds at 610k, but that would not be a scaling of your speed).
-Curtis[/quote]

You are correct. The machine that I'm running k=5 on is my Dell core-2 duo work laptop that I'm typing from right now. It's the only machine that I can see throughout the day and I like seeing up-to-the-minute progress of 'important' efforts like this. :smile: The other two Dell duos are my own laptops that I bought about 2 months after discovering these prime searching efforts because I liked my work laptop so much. (I think I'm going to wish I had waited and bought a super-speed quad like Carlos.) All the rest of my machines are my own except for one very older slow laptop (0.8 Ghz I think) that I borrowed from a friend that I only use for sieving in my all-twin effort.

Question...what about the CPU specs told you that it was a laptop?


Gary

em99010pepe 2007-10-19 17:46

Gary,

My super-speed quad, which is not, was cheaper than your T5500 laptop.

Carlos

VBCurtis 2007-10-20 00:27

Two things told me it was laptop:
First, model number is 5500. The desktop chips are 6xxx or 4xxx.
Second, 1.66Ghz is slower than any desktop part released except the 4300, a 1.6Ghz price leader. 1.66 was never released as a desktop speed. The 4xxx series are 800 bus speed, multiples of 200 for CPU speed. 6xxx are 1066 bus (6x50 is 1333 bus, recently released), so some odd speeds happen ending in 66.

Mine is a 6300 model, stock speed 1866/1066 bus. It's currently at 2840/1624 bus, and survived an expected 92F day today without AC or any errors. I love overclocking. Cruelty would be so proud.
-Curtis


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