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Old 2019-07-16, 04:12   #1
dcheuk
 
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Default Intermittent Slowdown

On one of my computer it seems like once in a while it produced a line that looks like this:

Code:
[Jul 15 05:01] Iteration: 43620000 / 52503887 [83.07%], ms/iter: 1502.254, ETA: 154d 11:10
[Jul 15 05:04] Iteration: 43630000 / 52503887 [83.09%], ms/iter: 15.726, ETA: 38:45:46
[Jul 15 05:06] Iteration: 43640000 / 52503887 [83.11%], ms/iter: 15.692, ETA: 38:38:13
[Jul 15 05:09] Iteration: 43650000 / 52503887 [83.13%], ms/iter: 15.700, ETA: 38:36:49
[Jul 15 09:15] Iteration: 43660000 / 52503887 [83.15%], ms/iter: 1478.413, ETA: 151d 07:55
[Jul 15 15:45] Iteration: 43670000 / 52503887 [83.17%], ms/iter: 2340.166, ETA: 239d 06:25
[Jul 15 15:48] Iteration: 43680000 / 52503887 [83.19%], ms/iter: 15.879, ETA: 38:55:15
[Jul 15 15:50] Iteration: 43690000 / 52503887 [83.21%], ms/iter: 15.684, ETA: 38:24:00
[Jul 15 15:53] Iteration: 43700000 / 52503887 [83.23%], ms/iter: 15.687, ETA: 38:21:48
[Jul 15 15:56] Iteration: 43710000 / 52503887 [83.25%], ms/iter: 15.843, ETA: 38:42:02
[Jul 15 15:58] Iteration: 43720000 / 52503887 [83.27%], ms/iter: 15.699, ETA: 38:18:15
[Jul 15 16:00] Running Jacobi error check.  Passed.  Time: 66.597 sec.
[Jul 15 16:02] Iteration: 43730000 / 52503887 [83.28%], ms/iter: 16.238, ETA: 39:34:33
[Jul 15 16:05] Iteration: 43740000 / 52503887 [83.30%], ms/iter: 15.783, ETA: 38:25:17
[Jul 15 20:10] Iteration: 43750000 / 52503887 [83.32%], ms/iter: 1470.032, ETA: 148d 22:34
[Jul 15 20:12] Iteration: 43760000 / 52503887 [83.34%], ms/iter: 15.830, ETA: 38:26:58
[Jul 15 20:15] Iteration: 43770000 / 52503887 [83.36%], ms/iter: 15.702, ETA: 38:05:36
[Jul 15 20:18] Iteration: 43780000 / 52503887 [83.38%], ms/iter: 15.684, ETA: 38:00:28
[Jul 15 20:20] Iteration: 43790000 / 52503887 [83.40%], ms/iter: 15.695, ETA: 37:59:26
[Jul 15 20:23] Iteration: 43800000 / 52503887 [83.42%], ms/iter: 15.706, ETA: 37:58:21
[Jul 15 20:26] Iteration: 43810000 / 52503887 [83.44%], ms/iter: 15.685, ETA: 37:52:47
[Jul 15 23:08] Stopping primality test of M52503887 at iteration 43814334 [83.44%]
[Jul 15 23:08] Worker stopped while running needed benchmarks.
[Jul 15 23:09] Benchmarks complete, restarting worker.
[Jul 15 23:09] Worker stopped.
[Jul 15 23:09] Worker starting
[Jul 15 23:09] Running Jacobi error check.  Passed.  Time: 17.397 sec.
[Jul 15 23:09] Resuming primality test of M52503887 using FMA3 FFT length 2800K, Pass1=448, Pass2=6400, clm=4, 4 threads
[Jul 15 23:09] Iteration: 43814335 / 52503887 [83.44%].
[Jul 15 23:10] Iteration: 43820000 / 52503887 [83.46%], ms/iter:  4.920, ETA: 11:52:05
[Jul 15 23:11] Iteration: 43830000 / 52503887 [83.47%], ms/iter:  5.336, ETA: 12:51:26
[Jul 15 23:12] Iteration: 43840000 / 52503887 [83.49%], ms/iter:  5.157, ETA: 12:24:38
[Jul 15 23:12] Iteration: 43850000 / 52503887 [83.51%], ms/iter:  5.209, ETA: 12:31:14
Just suddenly takes a long time and drops speed dramatically. I noticed this today again when one of my computers returns a negative ETA date. Does this signify a failing computer?

Thanks.

Last fiddled with by dcheuk on 2019-07-16 at 04:13
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Old 2019-07-16, 04:45   #2
axn
 
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Most likely some background process is stealing your cpu cycles during these times.
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Old 2019-07-16, 05:03   #3
dcheuk
 
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Quote:
Originally Posted by axn View Post
Most likely some background process is stealing your cpu cycles during these times.
That was what I was thinking, but this computer has absolutely nothing installed other than Prime95. I did a clean OS install (Mac OS Sierra) after I found it laying around in the garage, and has been running Prime95 ever since. Weird.

I'm going to try change the priority from 1 to 10 and see if anything changes lol.

Thanks!
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Old 2019-07-16, 05:10   #4
axn
 
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Another possibility is computer going to sleep/standby on its own.
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Old 2019-07-16, 07:43   #5
LaurV
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I would blame an antivirus (file scan) or task scheduler (for example, you don't need "something installed", even windoze's search indexer can take ages, especially if you have many small files and slow hdd). Check your scheduler and kill the thingies you don't need. It may also be your cat or dog playing games when you don't look...
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Old 2019-07-16, 17:41   #6
kriesel
 
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To summarize what others have said, and expand on it a bit:

Power saving: check profile selected, check its settings, eradicate anything related to cpu power or speed reduction. On Windows that involves setting timings to "never". MAC OS no doubt has equivalents.

If it's a laptop, leave the lid up/open somewhat.
I've found that some laptop systems nap under prime95 load if the lid is shut, even with all power settings set not to; thermal protection is king, and they count in their cooling budget on convection off the keyboard! Some are thermally marginal under prime95 load.

If you have cats, set a laptop lid at an angle that will prevent a cat from walking across the keyboard or laying on it. Cats like the warmth. The laptop does not like the heated furry blanket, nor the numerous pseudorandom keypresses or long-held key. Desktop keyboards leaned against the end of a desk cut down on that. Cats tend not to mess with the plastic mice though.

Check for OS tasks happening in the background; backup, search indexing, virus/security checks, patch downloading, etc. Also any applications that self-update. Sometimes such things are well behaved up to a certain point on the calendar or to a certain rev level and start consuming much larger resources, including cpu time (periodically a whole core for hours, for example). I've had gpu-vendor-supplied update-check software occupy a full core or more continuously if run.

Check for any file sharing or peer to peer sharing/updating. (Bit-torrent?)

To truly get these background cpu suckers under control, not only kill the process, but disable their launch.

Check logs for clues what's happening or what roughly coincides in time frame with the slowdowns. Perhaps increase logging.

Last fiddled with by kriesel on 2019-07-16 at 17:58
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Old 2019-07-17, 23:25   #7
dcheuk
 
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Quote:
Originally Posted by kriesel View Post
I've found that some laptop systems nap under prime95 load if the lid is shut, even with all power settings set not to; thermal protection is king, and they count in their cooling budget on convection off the keyboard! Some are thermally marginal under prime95 load.
This was the problem. For some reason the macbook doesn't allow Prime95 to run at full power when the lid is closed. This was not a problem for any of my Win10 laptops. Changing to no-sleep or disabling app-nap did nothing but leaving the lid on worked!

Quote:
Originally Posted by kriesel View Post
Cats like the warmth. The laptop does not like the heated furry blanket, nor the numerous pseudorandom keypresses or long-held key.


Thanks, you guys are very helpful.
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Old 2019-07-18, 00:35   #8
kriesel
 
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Glad your issue is solved.

At one point I was running prime95 on 6 laptops. I ran them from another floor of the house by remote desktop. Occasionally one or another would go catatonic because of cat-atop-it. It probably helped diagnosing the mechanism, that they were lined up on a very long shelf and I saw some serial correlation in the lineup, from the left, an easily accessed shelf end from a nearby desk, to the right, a high leap from the floor. (Laptop shuts down, cools down, cat relocates to a warmer seat, and repeat. Occasionally some had bizarre character strings displayed in the command prompt boxes as a result of the stroll.) It turns out that cats don't like to lie on inclined laptops, so wedging an old box of floppies or whatever under the front where it won't block air flow also works.

She was also fond of curling up in the exhaust of the bigger tower systems in the winter. Shed fur removal from grilles is recommended regular maintenance.

Last fiddled with by kriesel on 2019-07-18 at 00:39
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