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-   -   high average load and kernel recompilation (http://www.linux-archive.org/ubuntu-user/249853-high-average-load-kernel-recompilation.html)

Pol 02-21-2009 01:39 PM

high average load and kernel recompilation
 
Probably due to many applications always running, the average load of my
laptop, as reported by the 'top', is constantly around 5-6, users' cpu
percentage being around 90%, with no special application taking most of
that.
Any hints to lower the load?
Would kernel recompilation improve performance? (i am using kubuntu 8.04.2)

Thank you
--P



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Mario Vukelic 02-21-2009 02:35 PM

high average load and kernel recompilation
 
On Sat, 2009-02-21 at 15:39 +0100, Pol wrote:
> Probably due to many applications always running, the average load of my
> laptop, as reported by the 'top', is constantly around 5-6, users' cpu
> percentage being around 90%, with no special application taking most of
> that.

I think you want to investigate in more detail what is going on. This
seems not normal, unless you have a very old system or have very
demanding stuff running.

What are your hardware specs?

What *exactly* does it mean when you write, "many applications always
running"? How many, which ones, what are they doing (i.e., just
idling?). If your answer is "folding@home" then we can stop wasting time
right there :)

> Would kernel recompilation improve performance? (i am using kubuntu 8.04.2)

That's easy: no, not noticeably. Though it is worth to check which one
of the precompiled kernels you are running. Try "uname -r" on the
command line and report the output here.


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Pol 02-21-2009 04:58 PM

high average load and kernel recompilation
 
Mario Vukelic wrote:
> What are your hardware specs?

It is hp tc4200 laptop, 1.7 GHz (but i am used to keep it in 'powersave'
mode, at 0.8GHz) , 1.5MB ram, 2GB swap.

>
> What *exactly* does it mean when you write, "many applications always
> running"? How many, which ones, what are they doing

As i log in, several system services are started: postfix, dovecot, dictd,
hpoj, wooffle, collectd. I one of my attempts, proxy was disabled in
webbrowsers, with no change in performance, so my guess is that wwwoffle
should not affect the average load.
After log in, a few applets (kbandwidth, clock, calendar, systray), two
konsoles monitoring log files with 'tail -f', amarok are started and, from
a few more konsole sessions, 'sudo su' to four more users.
So, there are five users, each of which starts konqueror, connects to gmail,
opens a few pdf files, starts kalarm and kgmailnotifier; sometimes lyx
editors and maxima (symbolic computations, spending most of the time as
idle) are started.
One of those users starts ktorrent; another one starts knode; another one
starts firefox (connecting to gmail and opening several google notebooks)


> That's easy: no, not noticeably. Though it is worth to check which one
> of the precompiled kernels you are running. Try "uname -r" on the
> command line and report the output here.
'uname -r' returns:

2.6.24-23-generic


Thank you
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Pol 02-21-2009 09:59 PM

high average load and kernel recompilation
 
Probably due to many applications always running, the average load of my
laptop, as reported by the 'top', is constantly around 5-6, users' cpu
percentage being around 90%, with no special application taking most of
that.
Machine is hp tc4200 laptop, 1.7 GHz (but i am used to keep it
in 'powersave'
mode, at 0.8GHz) , 1.5MB ram, 2GB swap.

About running processes:
As i log in, several system services are started: postfix, dovecot, dictd,
hpoj, wooffle, collectd. I one of my attempts, proxy was disabled in
webbrowsers, with no change in performance, so my guess is that wwwoffle
should not affect the average load.
After log in, a few applets (kbandwidth, clock, calendar, systray), two
konsoles monitoring log files with 'tail -f', amarok are started and, from
a few more konsole sessions, 'sudo su' to four more users.
So, there are five users, each of which starts konqueror, connects to gmail,
opens a few pdf files, starts kalarm and kgmailnotifier; sometimes lyx
editors and maxima (symbolic computations, spending most of the time as
idle) are started.
One of those users starts ktorrent; another one starts knode; another one
starts firefox (connecting to gmail and opening several google notebooks)


Any hints to lower the load?
Would kernel recompilation improve performance? (i am using kubuntu 8.04.2,
kernel 2.6.24-23-generic)

Thank you
--P


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Mario Vukelic 02-22-2009 03:32 AM

high average load and kernel recompilation
 
On Sat, 2009-02-21 at 18:58 +0100, Pol wrote:
> It is hp tc4200 laptop, 1.7 GHz

Ah, a tablet. I know that one from the company, it's pretty slow. It's a
single-core CPU, right (Intel Pentium M 760?)

> (but i am used to keep it in 'powersave'
> mode, at 0.8GHz) ,

What does this mean? AFAIK Ubuntu (and I would guess Kubuntu) uses an
on-demand CPU governor by default. That is, it will let the CPU run at
full speed whenever needed, but throttle it otherwise. This is
independent from whether the laptop is plugged in or not.

So, my question would be, did you change that, and do you keep your CPU
throttled to a fixed speed even if you have high load? In this case you
should look no further for now and see whether the load continues to be
so high on average even it the CPU runs at full speed. After all, you'd
be throttling it to less than half its (less than spectacular as it is)
speed.

> As i log in, several system services are started: postfix, dovecot, dictd,
> hpoj, wooffle, collectd. I one of my attempts, proxy was disabled in
> webbrowsers, with no change in performance, so my guess is that wwwoffle
> should not affect the average load.
> After log in, a few applets (kbandwidth, clock, calendar, systray), two
> konsoles monitoring log files with 'tail -f', amarok are started and, from
> a few more konsole sessions, 'sudo su' to four more users.
> So, there are five users, each of which starts konqueror, connects to gmail,
> opens a few pdf files, starts kalarm and kgmailnotifier; sometimes lyx
> editors and maxima (symbolic computations, spending most of the time as
> idle) are started.
> One of those users starts ktorrent; another one starts knode; another one
> starts firefox (connecting to gmail and opening several google notebooks)

Um. You are running 5 users concurrently from a tc 4200 (possibly even
throttled?) and you complain about an average load of 5?

I run one user on an HP nc6400 (2GB RAM) with evolution, terminal(s),
firefox, liferea, video player, and transmission. I currently have load
average: 0.22, 0.81, 1.42

I dunno, to me this sounds like "to be expected", but maybe someone else can chip in,

> 2.6.24-23-generic

That's fine, you won't get any noticabe difference over the "generic"
flavor by recompiling, I don't think.


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Pol 02-22-2009 06:41 AM

high average load and kernel recompilation
 
<posted & mailed>

Mario Vukelic wrote:
> Ah, a tablet. I know that one from the company, it's pretty slow. It's a
> single-core CPU, right (Intel Pentium M 760?)
yes, it is Pentium M

>> (but i am used to keep it in 'powersave'
>> mode, at 0.8GHz) ,
> What does this mean? AFAIK Ubuntu (and I would guess Kubuntu) uses an
> on-demand CPU governor by default.
Yes that is the default, but it can be changed. That helps to keep laptop
from overheating (fan is working, yet it starts only at very high
temperature)

>
> So, my question would be, did you change that, and do you keep your CPU
> throttled to a fixed speed even if you have high load? In this case you
> should look no further for now and see whether the load continues to be
> so high on average even it the CPU runs at full speed. After all, you'd
> be throttling it to less than half its (less than spectacular as it is)
> speed.

'powersave' policy has been set, even when it is mains powered. That keeps
frequency at 800MHz. I have seen no option about throttling.
I had made an experimennt to compare loading at 1.7GHz and 0.8GHz and found
that, at 1.7GHz, loading lowered of about 1 - 1.5
How do you explain that cpu frequency affects loading?

>
>
> Um. You are running 5 users concurrently from a tc 4200 (possibly even
> throttled?) and you complain about an average load of 5?

I don't see any 'throttling' option

> I run one user on an HP nc6400 (2GB RAM) with evolution, terminal(s),
> firefox, liferea, video player, and transmission. I currently have load
> average: 0.22, 0.81, 1.42

So, five similar users would rise load to about 1?
Here firefox takes about 17% of my cpu time.
Other heavy programs are nspluginviewers (7-17 %), ktorrent (10%), konqueror
(3-10%, each one of them), Xorg itsef (5-15%)

>
> I dunno, to me this sounds like "to be expected", but maybe someone else
> can chip in,

Thanks
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Mario Vukelic 02-22-2009 10:03 AM

high average load and kernel recompilation
 
On Sun, 2009-02-22 at 08:41 +0100, Pol wrote:
> Yes that is the default, but it can be changed. That helps to keep laptop
> from overheating (fan is working, yet it starts only at very high
> temperature)

Got it

> 'powersave' policy has been set, even when it is mains powered. That keeps
> frequency at 800MHz.

Got it

> I have seen no option about throttling.

It's just another word for powersave

> I had made an experimennt to compare loading at 1.7GHz and 0.8GHz and found
> that, at 1.7GHz, loading lowered of about 1 - 1.5

Ok, that's to be expected and a good result i guess

> How do you explain that cpu frequency affects loading?

Oh, so you are a bit confused bout what the load actually is :)
Well, the load is calculated in relation to your CPU utilization. If you
put you CPU into powersave, it will be more fully utilized for the same
tasks than if it runs at full speed. So the load will rise.

It's really like comparing 2 computers that are identical except that
the CPU of one of them is half as fast as the other. If you want them to
perform the same tasks, he slower one will have to work a higher
percentage of the time, and thus will have a higher system load.

The Wikipedia article is well-written and should explain it all:
http://en.wikipedia.org/wiki/Load_(computing)


> > Um. You are running 5 users concurrently from a tc 4200 (possibly even
> > throttled?) and you complain about an average load of 5?
>
> I don't see any 'throttling' option

As above, just a different word for CPU powersave

> So, five similar users would rise load to about 1?

Depends on what they are doing. If they are all idle, it should not
change load much. But if as a result 5 times the programs of a single
user end up fightung for CPU time, then yes

> Here firefox takes about 17% of my cpu time.
> Other heavy programs are nspluginviewers (7-17 %), ktorrent (10%), konqueror
> (3-10%, each one of them), Xorg itsef (5-15%)

Add it all up and you are at 100% or not much below



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