boinc resource usage

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bugmenot

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Message 1921 - Posted: 15 Dec 2005, 10:08:39 UTC

When I run boinc, I get very high "% ni" values shown in top (FC4).

I had assumed the ni value was a % nice value, but I can't see how this makes sense. What is "% ni", and why does boinc cause it to be high?
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Bill Michael

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Message 1941 - Posted: 15 Dec 2005, 17:16:12 UTC

BOINC is designed to use every single otherwise-unused CPU cycle on your computer. To do this without impacting other programs, it runs at "nice" priority, meaning "I'll get out of the way nicely when anything else needs time".

So, when BOINC is running, the "% nice" is very high, where before you ran BOINC, the "% idle" was very high. All the % figures will add up of course to 100 - BOINC is just 'moving' the largest figure from the idle column to the 'nice' column. This should have no impact on anything in any of the "real work done" columns.

On my Mac, for example, I'm seeing right now 6% "user", 14% "system", and 80% "nice", with 0% "idle". Since "idle" CPU seconds are "wasted", this looks good to me! :-)

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bugmenot

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Message 1983 - Posted: 16 Dec 2005, 7:24:54 UTC - in response to Message 1941.  

BOINC is designed to use every single otherwise-unused CPU cycle on your computer. To do this without impacting other programs, it runs at "nice" priority, meaning "I'll get out of the way nicely when anything else needs time".

So, when BOINC is running, the "% nice" is very high, where before you ran BOINC, the "% idle" was very high. All the % figures will add up of course to 100 - BOINC is just 'moving' the largest figure from the idle column to the 'nice' column. This should have no impact on anything in any of the "real work done" columns.

On my Mac, for example, I'm seeing right now 6% "user", 14% "system", and 80% "nice", with 0% "idle". Since "idle" CPU seconds are "wasted", this looks good to me! :-)


Thanks.

So is the nice value processor overhead (using 80% of the cpu) to keep boinc at a different niceness level?
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Bill Michael

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Message 1985 - Posted: 16 Dec 2005, 7:34:26 UTC - in response to Message 1983.  

So is the nice value processor overhead (using 80% of the cpu) to keep boinc at a different niceness level?


... I don't understand the question. I'm far from Linux-knowledgeable, I can only answer the ones that are "like the Mac does it". Hopefully someone else will be able to answer that.

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Paul D. Buck

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Message 1988 - Posted: 16 Dec 2005, 11:56:51 UTC - in response to Message 1983.  
Last modified: 16 Dec 2005, 11:57:20 UTC

So is the nice value processor overhead (using 80% of the cpu) to keep boinc at a different niceness level?

Not sure if I am going to answer this question correctly in the sense I am not sure I understand what you are asking.

On Bill's Mac, he had, effectively, 80% of his computer "idle" at the time he took his snapshot. BOINC mearly took this time and put it to use. On my dual G5 PowerMac I see roughly 90% nice at the moment with BOINC taking 90% (roughly) of each CPU.

This drops to the 40's/50's when doing something intense like my just launching iTunes ... now with iTunes running I get 85% to 90% nice with my CPUs getting high 80's to 90%, with one processor usually getting slightly more than the other.

I have only on rare occasions to find that BOINC, or SETI@Home Classic for that matter, actually causing a noticible slowdown ...

And Bill, OS-X *IS* Unix ... and so is Linux the name change a little bit thats all ...
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bugmenot

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Message 1992 - Posted: 16 Dec 2005, 13:28:18 UTC

Thanks for your reply.

To me, %nice sounds like the amount of time the kernel is spending attending to the niceness of each process, rather than doing something useful, like crunching numbers for boinc.

I suppose my question is - why is the %nice value so high, why isn't boinc showing up in %user?
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Bill Michael

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Message 2019 - Posted: 16 Dec 2005, 21:28:58 UTC - in response to Message 1992.  

To me, %nice sounds like the amount of time the kernel is spending attending to the niceness of each process, rather than doing something useful, like crunching numbers for boinc.

I suppose my question is - why is the %nice value so high, why isn't boinc showing up in %user?


Ah. No, you have the wrong definition of %nice. The kernal is in "system" priority. Programs you run are in "user" priority. BOINC does not want to compete against your web browser and such, so it is in "nice" priority. The thing that top is measuring is how much time is given to the processes that are running at each priority.

Example: We'll take one single CPU second, and divide it up into 100 parts, and look at what is happening in each of those little time slices.

During 6 of these little slices, the OS is doing it's "housekeeping", moving packets across the network, refreshing your screen, updating your clock, seeing where the mouse is, and deciding which of the _other_ slices to give to which program.

During 14 of these slices, your web browser was redrawing that animated GIF, your email program went out and checked for new mail, and your MP3 player sent some music to the speakers.

During the remaining 80 slices, there was nothing to do. If BOINC was not running, the CPU would just fall into an "idle" state and literally do nothing. But, BOINC is running, so the CPU crunched another 1/100000 of a SETI result instead.

In the _next_ second, we ask "what is my computer doing", and we get "6% system, 14% user, 80% nice".

Hope that helps...

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bugmenot

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Message 2074 - Posted: 19 Dec 2005, 13:23:30 UTC - in response to Message 2019.  

To me, %nice sounds like the amount of time the kernel is spending attending to the niceness of each process, rather than doing something useful, like crunching numbers for boinc.

I suppose my question is - why is the %nice value so high, why isn't boinc showing up in %user?


Ah. No, you have the wrong definition of %nice. The kernal is in "system" priority. Programs you run are in "user" priority. BOINC does not want to compete against your web browser and such, so it is in "nice" priority. The thing that top is measuring is how much time is given to the processes that are running at each priority.

Example: We'll take one single CPU second, and divide it up into 100 parts, and look at what is happening in each of those little time slices.

During 6 of these little slices, the OS is doing it's "housekeeping", moving packets across the network, refreshing your screen, updating your clock, seeing where the mouse is, and deciding which of the _other_ slices to give to which program.

During 14 of these slices, your web browser was redrawing that animated GIF, your email program went out and checked for new mail, and your MP3 player sent some music to the speakers.

During the remaining 80 slices, there was nothing to do. If BOINC was not running, the CPU would just fall into an "idle" state and literally do nothing. But, BOINC is running, so the CPU crunched another 1/100000 of a SETI result instead.

In the _next_ second, we ask "what is my computer doing", and we get "6% system, 14% user, 80% nice".

Hope that helps...


Thanks for this. So just to clarify - any process running with lower of higher niceness shows in the percentage nice value?
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lidden

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Message 2076 - Posted: 19 Dec 2005, 16:17:49 UTC - in response to Message 2074.  


Thanks for this. So just to clarify - any process running with lower of higher niceness shows in the percentage nice value?


Processes with nice larger than 0 shows up in the nice value. Not those with negative nice, only root can run with negative nice level.

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Message boards : BOINC client : boinc resource usage

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