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11) Message boards : Number crunching : Once in a Blue Moon Challenge (Message 151196)
Posted 33 days ago by Profile Michael GoetzProject donor
Why is the abortion-rate that high?
I mean, i too aborted around 10 %, to "realign" the WUs with some DC-tasks, but that high a percentage?
Any ideas?

There are many scenarios in which you download more tasks than you actually want to run and abort some of them – maybe by some logic. Some of them were outlined by others above, but I'ld like to point out one more.

There's a bug in BOINC where – if you don't have any tasks for some subproject in your client_state.xml or whatever and you start running that subproject, it will download one task per each core (as if you were going to run one task per core), independent of the settings of how many cores per task you've set for the subproject. So it's very possible to get way too many tasks downloaded at the start of the challenge like this and abort most of them.

Maybe this was fixed or alleviated by the changes with how you can set multi-threading from the server side preferences now, I wouldn't know for sure (haven't crunched in... years now).


Very likely the high abort rate is from DC task hunting. With the long running llrPSP tasks,
you may have a large amount of time left after running your last long task that will finish
before the challenge ends. So you can run DC tasks to use the remaining challenge time.
You do this by downloading 10 days of tasks, aborting all the long tasks, and keeping the
DC tasks to do after your last long task finishes


While that's indeed a plausible and reasonable explanation, the actual explanation is that it's mostly due to a single broken computer -- most likely with its system date set in the future -- that is continuously and automatically aborting all tasks as soon as they're received. It's certainly not intentional.
12) Message boards : Number crunching : Once in a Blue Moon Challenge (Message 151191)
Posted 33 days ago by Profile Michael GoetzProject donor
(...)
This computer probably isn't even set up to run the challenge as it's doing this on many of the sub-projects. It's doing more PSP than others because the server is set to favor challenge tasks (this improves performance.)

So there you have it. The big number of aborts is mostly due to a single broken computer.


Interesting - and good explanation which with lacking insight i could not deduce.

by the way: I changed my E5-2690 out and my E5-2670 v3 in, now 2 tasks were started with AVX and are completed with FMA3, is this a game breaker? Should i abort the tasks, or would they come out just fine?

(since nobody asked - i swapped the ssd, since the CPUs won't fit in the same board. ;) )


2 x 2 = 4 no matter whether you use AVX or FMA3 to do the multiply, so you're fine. The transform is used to get from step N to step N+1, but the result is the same no matter the method you use to do the math. The checkpoints are done between completed steps.

You can also change the number of threads between saves, although it's a bit tricky to get both BOINC and LLR to recognize the change.

That being said, completing the calculation correctly isn't the only thing you need to worry about. if you switched the CPU (and the motherboard too???) the BOINC server may (or may not) decide this is a brand new host. If it does, it will reject the tasks when they're returned. I suggest hitting the "Update" button, and see A) if there's any error messages in the log, and B) whether you see the computer with a new host ID on the PrimeGrid website.

If it created a new host, then yes, abort the tasks. If it didn't, it should be ok to continue running them.
13) Message boards : Number crunching : Once in a Blue Moon Challenge (Message 151186)
Posted 34 days ago by Profile Michael GoetzProject donor
Why is the abortion-rate that high?
I mean, i too aborted around 10 %, to "realign" the WUs with some DC-tasks, but that high a percentage?
Any ideas?


Well, you got me interested, so I took a look.

There's a few people with a *LOT* of aborted tasks. I dug deeper and... it's not some evil strategy to dominate the world. It's not actually anything interesting at all. It's mostly a single computer which is instantly aborting *all* of its tasks. When it only takes a few seconds per task, a single computer can break many thousands per day.

My guess is the clock on the computer is set wrong; specifically, it's set to sometime in the future beyond any of the tasks' deadlines. When this happens (and we've seen this before), as soon as BOINC downloads a tasks, it realizes (erroneously) that the tasks are past their deadline, and have not yet started to run. BOINC then immediately aborts the task. Rinse and repeat, ad infinitum.

This computer probably isn't even set up to run the challenge as it's doing this on many of the sub-projects. It's doing more PSP than others because the server is set to favor challenge tasks (this improves performance.)

So there you have it. The big number of aborts is mostly due to a single broken computer.
14) Message boards : Number crunching : Once in a Blue Moon Challenge (Message 151172)
Posted 34 days ago by Profile Michael GoetzProject donor
It would be very nice if there was a PG project switch to send ONLY DC tasks for LLR subprojects. Without such a switch, I will be forced to download a 10 day queue of PSP tasks, and then abort any that I can't finish in the time remaining.

If was discussed few times already and it's just not possible. To generate stable flow of DC tasks for just one computer, 64 slave computers working on main tasks will be required.


A DC ONLY switch ...


Let me help out with the word you're having trouble with...


impossible [ im-pos-uh-buhl ]

adjective

  1. not possible; unable to be, exist, happen, etc.
  2. unable to be done, performed, effected, etc.:
    an impossible assignment.
  3. incapable of being true, as a rumor.
  4. not to be done, endured, etc., with any degree of reason or propriety:
    an impossible situation.
  5. utterly impracticable:
    an impossible plan.
  6. hopelessly unsuitable, difficult, or objectionable.



(From dictionary.com.)

15) Message boards : Cullen/Woodall prime search : Future CW-sieve. (Message 150941)
Posted 58 days ago by Profile Michael GoetzProject donor
For base 2, the NVIDIA sieve is faster, but that sieve does not support other bases.


To be clear, there's no need for additional *G*CW sieving at this point (or anywhere in the near future.) The interest is only for base 2 sieving.
16) Message boards : Number crunching : PrimeGrid's 16th Birthday Challenge (Message 150641)
Posted 97 days ago by Profile Michael GoetzProject donor
And is it just me, or does the birthday cake banner only have 15 candles?


You observe correctly but, as discussed on Discord, the candles count from 0, & the 0th one isnt shown :).


We decided to leave a candle missing to honor all that was lost during the pandemic.
17) Message boards : Number crunching : remaning time (Message 150622)
Posted 98 days ago by Profile Michael GoetzProject donor
I keep getting cpu tasks which show remaining time as over 9 days with a deadline of 6 days so I keep having to abort them as I will not get any points for them and every time they upload I get another one so it must be time to stop the project which is sad as I have over 160 million points and been doing it for over 12 years. can this be corrected so there is enough time remaining

Paul


Don't abort them.

1) Time estimates can be wrong for a variety of reasons.

2) As long as your computer is running the task, the server will extend the deadline as needed. See this thread for details.

3) If you return the correct result, you'll still get credit for it even if it's past the deadline, provide the task hasn't been purged from the database. (Which would be really, really late.)
18) Message boards : Number crunching : Flops decreasing (Message 150603)
Posted 100 days ago by Profile Michael GoetzProject donor
One of the first definitions of the Cobblestone (the unit of BOINC credits) was 1 GigaFLOPS == 200 Cobblestones. This is what the standard BOINC server code still uses for the "Current GigaFLOPS" on the server status page, it is just the cumulated RAC of all participants divided by 200. PrimeGrid obviously changed the code to show TeraFLOPS instead of GigaFLOPS in order to avoid large numbers; I don't know if they also changed the formula.


I'm the person who added those statistics to PrimeGrid's server status page, so I can talk about this authoritatively.

As you say, the standard in BOINC servers is to use the GFLOP/Cobblestone formula to reverse engineer the total GFLOPs. I was not at all satisfied with this, as it's got many, many flaws, but to paraphrase, "It's the worst imaginable system; except for all the rest."

Any other way of calculating GFLOPs has worse problems, especially since we have some non-BOINC ways of getting credit such as PRPNet and manual sieving. But even without that, it would be very, very hard to "count" GFLOPs task by task accurately.

RAC is simply the best estimate we have of total GFLOPs.

Furthermore, it's the way *every* BOINC project does it, so it gives us an apples-to-apples comparison to everyone else. As flawed as it is, at least it's measuring the same thing at each project.

Getting back to the original question, I don't think anyone mentioned one of the major factors in the decrease: It's summer in the northern hemisphere. It's too hot to crunch.
19) Message boards : Problems and Help : How to abort tasks from PrimeGrid website? (Message 150515)
Posted 114 days ago by Profile Michael GoetzProject donor
It can't be done. The tasks will just time out and be resent by the server.
20) Message boards : Problems and Help : SGS is not listed in the Applications link (Message 150514)
Posted 114 days ago by Profile Michael GoetzProject donor
Why is it called TPS


Its original name was Twin Prime Search.


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