Which is the best CPU configuration?


log in

Advanced search

Message boards : Number crunching : Which is the best CPU configuration?

1 · 2 · Next
Author Message
Zapiao
Volunteer tester
Send message
Joined: 29 Oct 01
Posts: 110
Credit: 122,278
RAC: 0
Portugal
Message 1274709 - Posted: 24 Aug 2012, 3:59:21 UTC

Of 4 cores : 2 running at 100% or 4 running at 50% ?

Horacio
Send message
Joined: 14 Jan 00
Posts: 536
Credit: 75,123,648
RAC: 38,474
Argentina
Message 1274713 - Posted: 24 Aug 2012, 4:26:12 UTC - in response to Message 1274709.

Of 4 cores : 2 running at 100% or 4 running at 50% ?

It depends on your goal:
If you want the best crunching performance, both settings will be almost the same, probably 2 cores at 100% will be slightly better than 4 at 50% due to the overload caused by the constant start and stop of the threads.
If you want a more responsive system for other tasks, then use 2 cores at 100%.
If you want less heat, then use all of them throttled, but in this case it would be even better to use the Throttle app as it can be set to do a dynamic throttle based on the temps...


____________

Profile Link
Avatar
Send message
Joined: 18 Sep 03
Posts: 829
Credit: 1,571,941
RAC: 250
Germany
Message 1274763 - Posted: 24 Aug 2012, 7:14:36 UTC - in response to Message 1274709.

Of 4 cores : 2 running at 100% or 4 running at 50% ?

The answer to the question "Which is the best CPU configuration?" would be 4 cores @100%. What are the reasons, that you want your machine to idle half of the time?
____________
.

Profile S@NL - eFMer - efmer.com/boincProject donor
Volunteer tester
Avatar
Send message
Joined: 7 Jun 99
Posts: 512
Credit: 130,102,829
RAC: 33,936
United States
Message 1274775 - Posted: 24 Aug 2012, 7:58:15 UTC - in response to Message 1274709.

Of 4 cores : 2 running at 100% or 4 running at 50% ?

2 running at 100%
The other option causes more overhead, it stops and starts the application.

____________
TThrottle Control your temperatures. BoincTasks The best way to view BOINC. Anza Borrego Desert hiking.

Profile ausymark
Send message
Joined: 9 Aug 99
Posts: 70
Credit: 9,411,160
RAC: 261
Australia
Message 1274853 - Posted: 24 Aug 2012, 12:13:03 UTC - in response to Message 1274709.

Depends what your 4 cores are apart of, what your other application loads are, and how much memory you have.

4 cores on an Intel i7 are going to be more powerful than 4 cores on an Intel i3

Your application load may be light in relation to an i7, but heavy on an i3

And RAM wise running 2 copies (2 cores only) will use less RAM than 4 cores (4 seti copies)

Swapping to/from hard disk is also increased using 4 cores - however given a large enough write to disk time this is also negligible.

My recommendation would be to run 3 cores at 100% and see what the computers response is running other apps.

(Just make sure your CPU/Case has adequate cooling - CPU temps should stay under 85C to ensure long term cpu life.)

Just my 2c worth :)

Cheers

Mark


____________

Josef W. SegurProject donor
Volunteer developer
Volunteer tester
Send message
Joined: 30 Oct 99
Posts: 4305
Credit: 1,074,160
RAC: 1,197
United States
Message 1274965 - Posted: 24 Aug 2012, 18:30:11 UTC

The i3-380M has 2 physical cores but with hyperthreading can run as 4 logical cores (4 threads per Intel's convention).

The "2 running at 100%" scenario with hyperthreading on would be somewhat different from turning hyperthreading off, though Windows does understand about hyperthreading so would likely keep the 2 processes divided between the physical cores. In either case, "4 running at 50%" would be less productive. The general experience is that hyperthreading can increase productivity by maybe 25 to 30 percent when no other limitations are applied (4 at 100%).

The host also has an "ATI Radeon HD 5x00 series (Cedar) (512MB)" which could be used for AP processing. That's an additional reason to consider the 3 at 100% configuration Mark suggested. Having one logical core free to do the OS stuff and feed the GPU when it's crunching would IMO be best overall.

If there is concern about temperatures, using TThrottle is probably a better solution than BOINC's method of controlling usage.

Joe

Profile ausymark
Send message
Joined: 9 Aug 99
Posts: 70
Credit: 9,411,160
RAC: 261
Australia
Message 1275077 - Posted: 24 Aug 2012, 23:47:16 UTC - in response to Message 1274965.

lol It was late when I wrote that, I forgot that the i3's are only dual core. I was mainly used to demonstrate the point that a less powerful CPU may struggle under workloads that a more powerful CPU would breeze through.

The way I have my i7 2600K setup is that I have 4 physical cores running at 100%, this keeps all cores relatively busy. Using Hyperthreading on the the i7, which simulates 8 cores, leaves 4 virtual cores "free". These are used to run apps and feed my GPU - nVidia 580gtx.

This setup leaves the computer fluid and responsive for general use as we as enabling sufficient data flow to/from the GPU.

If I leave the PC running 24x7 it will reach RAC scores of over 40K, so it seems to work well for me.

Cheers

Mark
____________

Profile arkaynProject donor
Volunteer tester
Avatar
Send message
Joined: 14 May 99
Posts: 3692
Credit: 48,732,775
RAC: 6,049
United States
Message 1275093 - Posted: 25 Aug 2012, 1:21:14 UTC - in response to Message 1275077.

lol It was late when I wrote that, I forgot that the i3's are only dual core. I was mainly used to demonstrate the point that a less powerful CPU may struggle under workloads that a more powerful CPU would breeze through.

The way I have my i7 2600K setup is that I have 4 physical cores running at 100%, this keeps all cores relatively busy. Using Hyperthreading on the the i7, which simulates 8 cores, leaves 4 virtual cores "free". These are used to run apps and feed my GPU - nVidia 580gtx.

This setup leaves the computer fluid and responsive for general use as we as enabling sufficient data flow to/from the GPU.

If I leave the PC running 24x7 it will reach RAC scores of over 40K, so it seems to work well for me.

Cheers

Mark


I went the other way completely, all GPU and no CPU.
____________

Zapiao
Volunteer tester
Send message
Joined: 29 Oct 01
Posts: 110
Credit: 122,278
RAC: 0
Portugal
Message 1275098 - Posted: 25 Aug 2012, 1:59:38 UTC - in response to Message 1275093.

I choosed 3 cores at 100%.

Profile S@NL - eFMer - efmer.com/boincProject donor
Volunteer tester
Avatar
Send message
Joined: 7 Jun 99
Posts: 512
Credit: 130,102,829
RAC: 33,936
United States
Message 1275099 - Posted: 25 Aug 2012, 2:01:24 UTC - in response to Message 1275093.

I went the other way completely, all GPU and no CPU.

The other extreme.

____________
TThrottle Control your temperatures. BoincTasks The best way to view BOINC. Anza Borrego Desert hiking.

Grant (SSSF)
Send message
Joined: 19 Aug 99
Posts: 5868
Credit: 60,616,376
RAC: 47,473
Australia
Message 1275109 - Posted: 25 Aug 2012, 2:29:08 UTC - in response to Message 1275077.

The way I have my i7 2600K setup is that I have 4 physical cores running at 100%, this keeps all cores relatively busy. Using Hyperthreading on the the i7, which simulates 8 cores, leaves 4 virtual cores "free". These are used to run apps and feed my GPU - nVidia 580gtx.

I run WUs on all my available cores & 2 at a time on the GPU. No responsiveness problems.

____________
Grant
Darwin NT.

rob smithProject donor
Volunteer tester
Send message
Joined: 7 Mar 03
Posts: 8535
Credit: 59,487,653
RAC: 86,889
United Kingdom
Message 1275241 - Posted: 25 Aug 2012, 6:21:42 UTC

I run a six core AMD Phenom with a GTX460. I run six CPU tasks and two GPU tasks all the time with no response problems - even rotating big Autocad models its smooth enough (but I could do with a faster GPU as even without S@H running it can be a bit notchy - HOW MUCH!!!! for a GTX690, and will I be able to afford it before Nvidia drop the 790 on the market?)
____________
Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Profile Link
Avatar
Send message
Joined: 18 Sep 03
Posts: 829
Credit: 1,571,941
RAC: 250
Germany
Message 1275255 - Posted: 25 Aug 2012, 7:13:01 UTC - in response to Message 1275109.

I run WUs on all my available cores & 2 at a time on the GPU. No responsiveness problems.

Same here on my Athlon X2 system, 2 CPU tasks (2 cores without HT) + 2 tasks on the GPU. No issues, only for watching HD movies or playing games I suspend GPU processing.
____________
.

Zapiao
Volunteer tester
Send message
Joined: 29 Oct 01
Posts: 110
Credit: 122,278
RAC: 0
Portugal
Message 1275256 - Posted: 25 Aug 2012, 7:22:38 UTC - in response to Message 1274775.


The other option causes more overhead, it stops and starts the application.

Why boinc works that way? Why not always working instead of "start-stop"?
____________
By your command !!!

Zapiao
Volunteer tester
Send message
Joined: 29 Oct 01
Posts: 110
Credit: 122,278
RAC: 0
Portugal
Message 1275258 - Posted: 25 Aug 2012, 7:37:41 UTC - in response to Message 1275257.

[quote]
Why boinc works that way? Why not always working instead of "start-stop"?

There are many ways to run Boinc......stock....take what you get.
Opti....takes some additional input and upkeep to stay current.
You can choose what you wish.

Can you explain this better?
____________
By your command !!!

Horacio
Send message
Joined: 14 Jan 00
Posts: 536
Credit: 75,123,648
RAC: 38,474
Argentina
Message 1275501 - Posted: 25 Aug 2012, 20:09:06 UTC - in response to Message 1275256.


The other option causes more overhead, it stops and starts the application.

Why boinc works that way? Why not always working instead of "start-stop"?

Because if you set it to use only 50% of CPU time then it has to use it only half of the available time. So it starts the app and make it work for a time slice (a very short time of few cpu clock ticks) and then stops it until it´s time to run it again. If you want it to work always then you mut set it to use the 100% of CPU time (no throttle).

Remember that the idea behind this setting is to keep the CPU at low temps and low load, so this cant be made by running one app at full usage and then waiting some time before starting another. Clearly doing this will put the CPU on an even worst temp stress because it will be heating and cooling on a cyclic way which is one of worst thing you can make to an electronic device. Also, in this way, when the app starts then the CPU will be under high load so if you used this to avoid lag it will be completely uneffective.


____________

EdwardPF
Volunteer tester
Send message
Joined: 26 Jul 99
Posts: 239
Credit: 56,426,768
RAC: 72,662
United States
Message 1275515 - Posted: 25 Aug 2012, 20:42:13 UTC - in response to Message 1275257.

There are many ways to run Boinc......stock....take what you get.
Opti....takes some additional input and upkeep to stay current.
You can choose what you wish.


If you are willing to do some work ;-) ... you can set things up to run SETI on only the even numbered CPU's (the "real ones"). I have found that on my Core I-7 the even numbered CPU's are about 8% faster than the odd numbered CPU's.

Just a thought ...

Ed F

Profile T. Moe
Avatar
Send message
Joined: 31 May 12
Posts: 157
Credit: 1,241,163
RAC: 1
United States
Message 1280271 - Posted: 5 Sep 2012, 14:31:03 UTC
Last modified: 5 Sep 2012, 14:46:55 UTC

I've been reading this thread, and find I still don't have a good answer to my laptop. I use this laptop for day to day general use as well as running Seti@Home. I let seti run It all night, and most of the day.
It has 8 processors. What would be a good configuration. 8 CORES AT 100%, 100% of the time, 4 cores 100% etc etc. Just trying to keep it fairly cool for longevity,but at the same time running seti at a good pace.
Is this a unrealistic goal?
Any help would be appreciative.
____________

rob smithProject donor
Volunteer tester
Send message
Joined: 7 Mar 03
Posts: 8535
Credit: 59,487,653
RAC: 86,889
United Kingdom
Message 1280291 - Posted: 5 Sep 2012, 15:50:20 UTC

With a desk top its is generally best to run all the cores all the time, but with laptops they can get very hot, and some older ones may suffer from battery problems so it is probably best not to run them 24/7 unless you unplug the battery. (Guess who's got to get a new battery for his laptop...).

The exception for desktops is when running a more powerful ATI GPU, or a pile of high end Nvidia where you might find you need to dedicate a core to servicing the GPUs.
____________
Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

1 · 2 · Next

Message boards : Number crunching : Which is the best CPU configuration?

Copyright © 2014 University of California