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Leif Asbrink | 10 Apr 09:24

Re: Increased CPU usage

Hi All,

I recently wrote:
> Under RH9 I do not see the problem with normal parameters
> as those ones Daniel sent, but when setting silly parameters
> I see near 100% load with 02.28 while 02.21 shows only about
> 50% load.
.
.
.
This was just a mistake. I goofed with the parameter files 
and ended up running two channels under 02-21 but only a 
single channel under 02-28. A doubled work load is then 
quite reasonable........

When going back to Suse 9.1 I find I can not at all reproduce
my previous findings. Now, when running Daniels parameters
I find a CPU load of 5.9% with linrad-02.28 but with
Linrad 02-21 I find 23.5%. It is the other way around now -
and the times are clearly incorrect. The Pentium III can not do
the work with 5.9% CPU load!!

Checking with "system monitor" Shows the total load to be
identical, 42% for both Linrad versions. (9% when Linrad is not
running)

John was right:-)

There is a bug in the timing function under Suse 9.1!!
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Leif Asbrink | 8 Apr 15:44

Re: Increased CPU usage

Hello John,

Hmmm, in my experience the CPU load reported by the getrusage function
under Linux is quite reliable.

I do not know how I could use the parallel port to
show which thread is running in a multi-threaded
program like Linrad. As I understand it, threads 
can be stopped at any point in case the scheduler 
thinks it has been running too long. Sending a message
to the parallel port saying one particular thread is
waiting on a semaphore will not show all the times
when this particular thread is not running.

There is another way however. I can set silly parameters
in Linrad to provoke the CPU load to grow up to the point
where screen and mouse become affected. Under Suse 9.1 
this happens when the Linrad CPU meter shows 102% when
I run Linrad-02.28 on the Pentium III. With exactly the 
same parameters, (2 RF channels, fft1 window power of sin=6, 
fft2 window power of sin=2, slowest possible fft routines
and 2 x16 bits for audio output ) Linrad-02.21 runs happily
at a CPU load of 50% and I setting maximum window parameters
does not cause more than 60% CPU load with not even the 
slightest trace of any overload problem.

There is a real problem here. I have no idea what it is
but I have verified that it is present under good
old Red Hat 9 which still has the old implementation of
getrusage which reports CPU load individually for each
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John Harrison, NI1B | 8 Apr 13:33

Re: Increased CPU usage


Hi all,

   My experience with the OS telling me what the OS is doing is not good. 
Of course there are 'reasons' for whatever OS behaviour! But generally OS
numbers about OS usage are in my experience, total garbage.

   I find it better to put a bit out to the parallel port and measure what
is going on with an o-scope. 1 = busy, in linrad, whatever; 0 = in OS
(whatever that means). There are many parallel port bits so they can allow
one to time various routines, etc.

   If you do do this experiment, be prepared for the REAL surprises!!

   Just my humble opinion !!
   john

On Sun, 8 Apr 2007, Leif Asbrink wrote:

> Hello Daniel,
> 
> Thanks for info:-)
> 
> I am now able to reproduce similar results - but I
> have no idea at the moment what they mean.
> 
> I am looking at CPU load with and without sound output.
> Under Suse 9.1 I observe the following:
>                          Linrad-02.21   Linrad-02.28 
> PIV 2.66 GHz, Sound ON        8.3%            7.8%
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Leif Asbrink | 8 Apr 02:43

Re: Increased CPU usage

Hello Daniel,

Thanks for info:-)

I am now able to reproduce similar results - but I
have no idea at the moment what they mean.

I am looking at CPU load with and without sound output.
Under Suse 9.1 I observe the following:
                         Linrad-02.21   Linrad-02.28 
PIV 2.66 GHz, Sound ON        8.3%            7.8%
PIV 2.66 GHz, Sound OFF       4.3%            3.9%
PIII 800 MHz, Sound ON        24%             28%
PIII 800 MHz, Sound OFF       15%             17%
It is similar with svgalib, the X11 server is innocent ;-)

I have tried Red Hat 9 (kernel 2.4.20) on the Pentium III 
and I find 20% with sound on and 12% with sound OFF. It 
does not matter whether I try 02-21 or 02-28.

I will try some other Linux distributions on the 
PentiumIII to see if something interesting can be 
detected.

73

Leif / SM5BSZ

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Daniel Koch | 7 Apr 12:06
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Re: Increased CPU usage

Hello Leif,

I use VESA 1280x1024 @ 60Hz / 24bit with X11.

The values I sent before are with a signal selected. Percentages change a little with the selected filter
bandwidths (+-3%).

Without selecting a signal the figures are:
02.27:
no FFT2: 12%
with FFT2: 28%

02.19:
no FFT2: 9%
with FFT2: 26%

Hope it helps.

Daniel, DL3IAE

-------- Original-Nachricht --------
Datum: Fri, 6 Apr 2007 23:26:16 +0200
Von: Leif Asbrink <leif@...>
An: "Linrad mailinglist" <linrad@...>
Betreff: [linrad] Re: Increased CPU usage

> Hello Daniel,
> 
> I tried the parameters that you sent. (without fft2)
> These are the results:
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Leif Asbrink | 6 Apr 23:26

Re: Increased CPU usage

Hello Daniel,

I tried the parameters that you sent. (without fft2)
These are the results:

Pentium IV at 2.66 GHz, Debian Etch, Linrad-02-28: 4%
Pentium IV at 2.66 GHz, Debian Etch, Linrad-02.21: 5%
Pentium III at 800 MHz, Suse 9.1, Linrad-02.28: 7%
Pentium III at 800 MHz, Suse 9.1, Linrad-02.21: 18%

This is in terminal mode with svgalib.

Under X11 the load is similar on the Pentium IV
but it is about 16% on the Pentium III for both
Linrad-02.21 and 02-28.

Linrad-02-28 should be identical to 02-27 when it comes to
timings. The differences are in the calibration routines only.

The differences I see between the latest and earlier versions
go in the opposite direction to what you observe. The difference
(by a factor of about 2.5) is very large and shows that I 
corrected some error. Presumably I did not do it right since
you observe a change in the opposite direction.

Are you running with svgalib or under X11? If X11, what is the
screen size and colour depth that you use?

73
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Leif Asbrink | 6 Apr 15:05

Re: Increased CPU usage

Hello Daniel,

Thanks for the info. 
Please send the parameter files you used for this test.

I think the increased time is because of a bug of some
kind. I have not noticed this problem but I will look
at it in due time. At the moment I am working with
the calibration routines which do not work properly at
the moment. There are so many different situations and
it seems that changes I made recently go wrong now and 
then....

73

Leif

> Hello Leif,
> 
> there seems to be significant increase from 02.23 to 02.27 regarding the CPU usage.
> 
> On my system (AMD Duron 1,3 GHz, 512Mb RAM) I see the following figures:
> 
> Linux (Suse 9.1):
> 
> 02.19 (02.23 is the same)
> FFT2 off: 19%
> FFT2 on: 37%
> 
>
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