Freeing CPU cores


log in

Advanced search

Message boards : Number crunching : Freeing CPU cores

1 · 2 · 3 · 4 · Next
Author Message
bill
Send message
Joined: 16 Jun 99
Posts: 847
Credit: 20,555,523
RAC: 14,174
United States
Message 1400614 - Posted: 8 Aug 2013, 13:44:26 UTC

Has anyone posted the exact meaning of 'freeing up
a cpu core' in relation to gpu usage, and the where
and how to do so? And since there is more than one
way to do it, which would be the best/easiest/fastest
way to do it, in such a way that a newb would understand
it? A faq perhaps?

Profile Tazz
Volunteer tester
Avatar
Send message
Joined: 5 Oct 99
Posts: 137
Credit: 34,342,255
RAC: 1
Canada
Message 1400634 - Posted: 8 Aug 2013, 14:25:04 UTC - in response to Message 1400614.

Has anyone posted the exact meaning of 'freeing up
a cpu core' in relation to gpu usage, and the where
and how to do so? And since there is more than one
way to do it, which would be the best/easiest/fastest
way to do it, in such a way that a newb would understand
it? A faq perhaps?


I 'free up a core' in the local Preferences>processor usage tab. "On multiprocessor systems, use at most ___% of the processors."

I set mine at 90% and it crunches on 7 cores and leaves the 8th free.
75% on a 4 core system will leave 1 free

____________
</Tazz>

bill
Send message
Joined: 16 Jun 99
Posts: 847
Credit: 20,555,523
RAC: 14,174
United States
Message 1400639 - Posted: 8 Aug 2013, 15:09:52 UTC - in response to Message 1400634.

Yes, but is that for ATI or NVIDIA or is there a difference
between the two that newbs should be aware of.

Mine are set. I'm looking for something to point to when
a newb comes in that can be pointed at to answer their questions
while inflicting the minimum of pain on them.

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400659 - Posted: 8 Aug 2013, 15:48:23 UTC - in response to Message 1400639.
Last modified: 8 Aug 2013, 15:50:05 UTC

Yes, but is that for ATI or NVIDIA or is there a difference
between the two that newbs should be aware of.

Mine are set. I'm looking for something to point to when
a newb comes in that can be pointed at to answer their questions
while inflicting the minimum of pain on them.


Works for both.

90% doesn`t free a full core.
On a 8 core the correct settings is 86% on a quad 75%.
____________

juan BFB
Volunteer tester
Avatar
Send message
Joined: 16 Mar 07
Posts: 4610
Credit: 232,667,235
RAC: 332,336
Brazil
Message 1400663 - Posted: 8 Aug 2013, 15:58:27 UTC - in response to Message 1400639.
Last modified: 8 Aug 2013, 16:01:48 UTC

Yes, but is that for ATI or NVIDIA or is there a difference
between the two that newbs should be aware of.

The unwrited rules is...
You need to free 1 core if you have a AMD CPU and want to crunch on the GPU (ATI or NV) even if you run only MB, if you run AP you need to add +1 free core per GPU WU (AMD or Intel CPU).

To be sure the % to use just do the following math: 100*(1-(free cores needed)/(processor number of cores))

On I5 or Quad a processor number of cores = 4
On I7 processor number of cores =8 without HT or 4 with HT enabled
Same works with AMD or other Intels CPU´s.

It´s clear now?
____________

Profile William
Volunteer tester
Avatar
Send message
Joined: 14 Feb 13
Posts: 1517
Credit: 6,898,212
RAC: 27,167
Message 1400673 - Posted: 8 Aug 2013, 16:33:52 UTC

With 8 cores one core is 12.5.

Anything less than 100 will free one core. (allow 7 tasks)
88 will free one core. (7 tasks)
87.5 - since it's allow' One core not used - 7 tasks
87 will free two cores.
80 - 6 out of 8 cores in use
75 - still 6
74 - 5
70 - 5

So, for ease of editing when you have 8 cores:

50 - 4 cores used
70 - 5 cores used
80 - 6 cores used
90 - 7 cores used

And for a quad:

50 - 2 cores
75 - 3 cores (you could use 80 too)


____________
A person who won't read has no advantage over one who can't read. (Mark Twain)

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400675 - Posted: 8 Aug 2013, 16:40:01 UTC
Last modified: 8 Aug 2013, 17:19:50 UTC

edited
____________

Profile William
Volunteer tester
Avatar
Send message
Joined: 14 Feb 13
Posts: 1517
Credit: 6,898,212
RAC: 27,167
Message 1400677 - Posted: 8 Aug 2013, 16:42:53 UTC - in response to Message 1400675.

On a AMD CPU 88% isn`t enough.
At least on a FX 86% is needed.

86 should be freeing two cores - if you have more than 6 CPU tasks running, you've found a bug.
____________
A person who won't read has no advantage over one who can't read. (Mark Twain)

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400680 - Posted: 8 Aug 2013, 16:50:57 UTC - in response to Message 1400677.
Last modified: 8 Aug 2013, 17:19:31 UTC

[quote]
____________

Profile Tazz
Volunteer tester
Avatar
Send message
Joined: 5 Oct 99
Posts: 137
Credit: 34,342,255
RAC: 1
Canada
Message 1400682 - Posted: 8 Aug 2013, 16:52:56 UTC - in response to Message 1400677.
Last modified: 8 Aug 2013, 16:53:45 UTC

On a AMD CPU 88% isn`t enough.
At least on a FX 86% is needed.

86 should be freeing two cores - if you have more than 6 CPU tasks running, you've found a bug.


My FX 8150 is set to use 90% and it's crunching 7:
08/08/2013 11:13:54 AM | | max CPUs used: 7

One core should be enough for 2 GTX 560 with 2 wu's each, shouldn't it? The work times are similar to the GTX 560 in my other machine that has a free core (Phenom 9650) and 2 wu's. -- ONLY MB btw.
____________
</Tazz>

Profile William
Volunteer tester
Avatar
Send message
Joined: 14 Feb 13
Posts: 1517
Credit: 6,898,212
RAC: 27,167
Message 1400685 - Posted: 8 Aug 2013, 17:01:36 UTC - in response to Message 1400680.

On a AMD CPU 88% isn`t enough.
At least on a FX 86% is needed.

86 should be freeing two cores - if you have more than 6 CPU tasks running, you've found a bug.


More than one actually LOL.

Windows assigns upt to 13.5% to one CPU core.
So if you only reseverve 88% no full core is available.
This depends on the Win work scheduler.

I`ve tested this excessive in the last 2 years.

Well what BOINC does and what Windows does are different things.
88 will tell boinc to only run 7 tasks, 87 drops it to 6 tasks.

Those 7 cores will be fully used (depending on app) the remaining core then takes the normal load - so yes, technically not a full core is available.

For most people freeing most of a CPU core is enough.

____________
A person who won't read has no advantage over one who can't read. (Mark Twain)

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400686 - Posted: 8 Aug 2013, 17:03:17 UTC - in response to Message 1400682.
Last modified: 8 Aug 2013, 17:19:13 UTC

[quote]
____________

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400687 - Posted: 8 Aug 2013, 17:05:46 UTC - in response to Message 1400685.
Last modified: 8 Aug 2013, 17:18:52 UTC

edited
____________

Profile William
Volunteer tester
Avatar
Send message
Joined: 14 Feb 13
Posts: 1517
Credit: 6,898,212
RAC: 27,167
Message 1400688 - Posted: 8 Aug 2013, 17:06:05 UTC - in response to Message 1400682.

On a AMD CPU 88% isn`t enough.
At least on a FX 86% is needed.

86 should be freeing two cores - if you have more than 6 CPU tasks running, you've found a bug.


My FX 8150 is set to use 90% and it's crunching 7:
08/08/2013 11:13:54 AM | | max CPUs used: 7

One core should be enough for 2 GTX 560 with 2 wu's each, shouldn't it? The work times are similar to the GTX 560 in my other machine that has a free core (Phenom 9650) and 2 wu's. -- ONLY MB btw.


Rule of thumb is one core per card. - You might want to try and free another core.

We've gone horribly offtopic by the way which is quite impolite to a new user. Where's a moderator when you need one...
____________
A person who won't read has no advantage over one who can't read. (Mark Twain)

Profile Mike
Volunteer tester
Avatar
Send message
Joined: 17 Feb 01
Posts: 22383
Credit: 29,301,959
RAC: 23,718
Germany
Message 1400691 - Posted: 8 Aug 2013, 17:12:00 UTC - in response to Message 1400688.
Last modified: 8 Aug 2013, 17:18:15 UTC

[quote]
____________

Profile cov_route
Avatar
Send message
Joined: 13 Sep 12
Posts: 264
Credit: 4,658,870
RAC: 12,863
Canada
Message 1400697 - Posted: 8 Aug 2013, 17:23:25 UTC

I suspect what I'm doing is different from almost everyone else:

I use the anonymous platform, not stock apps, so I can use app_info.xml.

In BOINC my settings are to use 100% of the CPU.

In app_info, for astropulse I set <avg_ncpus> and <max_ncpus> to 1, so it sets aside a core for each GPU job when they run.

For multibeam I don't free a core, I use the command line settings:

-cpu_lock -instances_per_device 2 -gpu_lock

which set the GPU jobs to run on an assigned single core. For my Phenom II, at least, that works as well as idling a core.

Profile William
Volunteer tester
Avatar
Send message
Joined: 14 Feb 13
Posts: 1517
Credit: 6,898,212
RAC: 27,167
Message 1400704 - Posted: 8 Aug 2013, 17:27:54 UTC

To answer the original question: if anyone writes a FAQ entry I'll be delighted to post it in the Lunatics FAQ section.
____________
A person who won't read has no advantage over one who can't read. (Mark Twain)

mherr170
Avatar
Send message
Joined: 15 Nov 12
Posts: 245
Credit: 3,894,469
RAC: 11,936
United States
Message 1400755 - Posted: 8 Aug 2013, 19:04:05 UTC

I am just days away from trying to get my first AMD graphics card going on a rig.

Is freeing up a core something I only need to worry about for AMD cards? So far with NVidia cards, my graphics card task usually says something like (1 NVIDIA GPU + 0.04 CPUs)

Profile ignorance is no excuse
Avatar
Send message
Joined: 4 Oct 00
Posts: 9529
Credit: 44,432,110
RAC: 163
Korea, North
Message 1400804 - Posted: 8 Aug 2013, 21:11:55 UTC - in response to Message 1400755.

try running your nvidia card with a free core for a few WU cycles see if it improves(decreases) your GPU WU completion times
____________
In a rich man's house there is no place to spit but his face.
Diogenes Of Sinope

End terrorism by building a school

Profile Raistmer
Volunteer developer
Volunteer tester
Avatar
Send message
Joined: 16 Jun 01
Posts: 3276
Credit: 40,778,895
RAC: 60,493
Russia
Message 1400837 - Posted: 8 Aug 2013, 23:13:46 UTC - in response to Message 1400697.


-cpu_lock -instances_per_device 2 -gpu_lock

which set the GPU jobs to run on an assigned single core. For my Phenom II, at least, that works as well as idling a core.


Did you try the same for AP and failed or just didn't try ?
AP and MB share GPU/CPU lock code so if it works for MB it should work for AP too (in theory and in latest builds)

____________
News about SETI opt app releases: https://twitter.com/Raistmer

1 · 2 · 3 · 4 · Next

Message boards : Number crunching : Freeing CPU cores

Copyright © 2014 University of California