2001-04-02 22:14:40

by BERECZ Szabolcs

[permalink] [raw]
Subject: [QUESTION] 2.4.x nice level

Hi!

I just noticed, that a process with nice level 19, gets some processor
time, even if there is another process, which would use all of the
processor time.
for example, there is a setiathome running at nice level 19, and a
bladeenc at nice level 0. setiathome uses 14 percent, and bladeenc uses 84
percent of the processor. I think, setiathome should use max 2-3 percent.
the 14 percent is way too much for me.
or is there any other way to run a process only if nothing uses the
processor?
with kernel 2.2.16 it worked for me.
now I use 2.4.2-ac20

Bye,
Szabi



2001-04-02 23:05:21

by Quim K Holland

[permalink] [raw]
Subject: Re: [QUESTION] 2.4.x nice level

>>>>> "BS" == BERECZ Szabolcs <[email protected]> writes:

BS> ... a setiathome running at nice level 19, and a bladeenc at
BS> nice level 0. setiathome uses 14 percent, and bladeenc uses
BS> 84 percent of the processor. I think, setiathome should use
BS> max 2-3 percent. the 14 percent is way too much for me.
BS> ...
BS> with kernel 2.2.16 it worked for me.
BS> now I use 2.4.2-ac20

Would it the case that bladeenc running on 2.4.2 spends more
time doing I/O? I am not saying that the userland makes more I/O
requests, but if the same set of I/O requests are taking longer
to complete on 2.4.2, then while bladeenc is waiting for their
completion, it is not so surprising that the other process uses
the otherwise-idle CPU cycles.



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2001-04-03 03:04:57

by L A Walsh

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Subject: Re: [QUESTION] 2.4.x nice level

Quim K Holland wrote:
>
> >>>>> "BS" == BERECZ Szabolcs <[email protected]> writes:
>
> BS> ... a setiathome running at nice level 19, and a bladeenc at
> BS> nice level 0. setiathome uses 14 percent, and bladeenc uses
> BS> 84 percent of the processor. I think, setiathome should use
> BS> max 2-3 percent. the 14 percent is way too much for me.
> BS> ...
> BS> with kernel 2.2.16 it worked for me.
> BS> now I use 2.4.2-ac20
---
I was running 2 copies of setiathome on a 4 CPU server
@ work. The two processes ran nice'd -19. The builds we were
running still took 20-30% longer as opposed to when setiathome wasn't
running (went from 45 minutes up to about an hour). This machine
has 1G, so I don't think it was hurting from swapping.

I finally wrote a script that checked every 30 seconds -- if the
load on the machine climbed over '4', the script would SIGSTOP the
seti jobs. Once the load on the machine fell below 2, it would
send a SIGCONT to them.

I was also running setiathome on my laptop for a short while --
but the fan kept coming on and the computer would get really hot.
So I stopped that. Linux @ idle doesn't seem to ever kick on
the fan, but turn on a CPU cruching program and it sure seemed
to heat up the machine. I still wonder how many kilo or mega watts
go to running dispersed computation programs. Just one of those
things I may never know....

-l

--
The above thoughts and | They may have nothing to do with
writings are my own. | the opinions of my employer. :-)
L A Walsh | Trust Technology, Core Linux, SGI
[email protected] | Voice: (650) 933-5338