Re: 2.4 Cpu usuage (display oddities more than anything)

Re: 2.4 Cpu usuage (display oddities more than anything)

[Linda Walsh]

Some oddities w/kapmd(2.4.0)...  If I sit in X and do nothing other than run top or
"vmstat 5", I get down to as low as 60% idle and 40% in system -- with kapmd getting
'charged' for the 40%.

Then I go and run 'freeamp' and the CPU usage goes to 100% idle, presumably because
kapmd never gets called because it's never in the idle loop for longer than 333ms.

It's just weird and unnatural.

Also forgive my ignorance but is it really possible playing VBR MP3's takes 0 measurable
CPU?  I've run the program for hours and a ps of 'freeamp' show either no measured cpu 
time or maybe 1 second...the kernel runs at at 100% idle for most of the time.
I thought mp3 decompression was a cpu intensive operation....weird...

I guess I'm thinking -- maybe time in kapmd should be counted as 'idle'?

-l
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Re: 2.4 Cpu usuage (display oddities more than anything)

[safemode]

Linda Walsh wrote:

> Some oddities w/kapmd(2.4.0)...  If I sit in X and do nothing other than run top or
> "vmstat 5", I get down to as low as 60% idle and 40% in system -- with kapmd getting
> 'charged' for the 40%.
>
> Then I go and run 'freeamp' and the CPU usage goes to 100% idle, presumably because
> kapmd never gets called because it's never in the idle loop for longer than 333ms.
>
> It's just weird and unnatural.
>
> Also forgive my ignorance but is it really possible playing VBR MP3's takes 0 measurable
> CPU?  I've run the program for hours and a ps of 'freeamp' show either no measured cpu
> time or maybe 1 second...the kernel runs at at 100% idle for most of the time.
> I thought mp3 decompression was a cpu intensive operation....weird...
>
> I guess I'm thinking -- maybe time in kapmd should be counted as 'idle'?
>

  freeamp is just that good.  I've seen 0% cpu usage with it on 2.4 and 2.2.   if you
notice closely, it does use  a percentage of cpu but it's so small that over the course of
time that the cpu usage of each process is averaged, it is closer to 0 than 1.  It is hands
down the best mp3 player i've seen out.

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Re: 2.4 Cpu usuage (display oddities more than anything)

[Pavel Machek]

Hi!

> Some oddities w/kapmd(2.4.0)...  If I sit in X and do nothing other than run top or
> "vmstat 5", I get down to as low as 60% idle and 40% in system -- with kapmd getting
> 'charged' for the 40%.

At least you can see how kapmd mechanism actually works.

> Then I go and run 'freeamp' and the CPU usage goes to 100% idle, presumably because
> kapmd never gets called because it's never in the idle loop for longer than 333ms.
> 
> It's just weird and unnatural.
> 
> Also forgive my ignorance but is it really possible playing VBR MP3's takes 0 measurable
> CPU?  I've run the program for hours and a ps of 'freeamp' show either no measured cpu 
> time or maybe 1 second...the kernel runs at at 100% idle for most of the time.
> I thought mp3 decompression was a cpu intensive
> operation....weird...

Those counters are running. Try this one:

/*
 * This is simple program which should show weak spots in linux's scheduler
 */

#include <stdio.h>
#include <time.h>
#include <sys/timeb.h>
#include <unistd.h>

int startgame;

int
ticks( void )
{
struct timeb tb;
int sec, msec;
ftime( &tb );
sec = tb.time - startgame;
msec = tb.millitm;
return sec * 1000 + msec;
}

void
main( int argc, char *argv[] )
{
int delta, badboy = 0, count = 1000000;
int t1, t2;

startgame = time(NULL);
if (argc>1) { 
  badboy = 1; 
  printf( "I'm a *BAD* boy! " );
  usleep( 100000 );
  t1 = ticks();
  usleep( 100000 );
  t2 = ticks();
  delta = t2-t1;
  printf( "And bad boys know that jiffie is %dmsec\n", delta );
  delta = 10;
  }
else { printf( "I'm a good boy.\n" ); delta = 20; }
while(1) {
  if ((ticks()-t1) % delta > ((delta * 17)/20))
    if (badboy)
      usleep(10000);
  if (!((--count)%100000)) { printf( "." ); fflush( stdout ); }
  if (!count) break;
  }
}

it used to work. Bad boy used to be charged 0% cpu even if it ate 70%

> I guess I'm thinking -- maybe time in kapmd should be counted as 'idle'?

-- 
I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care."
Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org
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