>From: Markus Plail <[EMAIL PROTECTED]>
>>>In addition, it may be that Linux does not report the load correctly
>>>when doing PIO to the drive.
>>This (sadly) is another issue, when using e.g. "top", one should
>>*not* look at the CPU-consumption of cdrecord, but have a look at
>>the "idle" time. You will find, that cdrecord e.g. uses 5% resources,
>>the other tasks maybe another 5%, but that idle-time (should be around
>>90% in this example) is only 10% or less.
>Well, I don't think this behaviour is wrong actually. What really eats
>up CPU time in PIO mode is the interrupt handling. So it's not
>cdrecord, that uses the CPU, but the system and that's they way it is
>shown in top. As system time.
You cannot meter the system load correctly if you use any of the system
commands!
If you like to know what happens, you need to meter the system load indirectly:
Start with this command:
/*--------------------------------------------------------------------------*/
main()
{
int i;
for (i=0; i < 2000000000; i++)
;
exit (0);
}
/*--------------------------------------------------------------------------*/
compile it _without_ optimizer. cc -o t t.c
Now switch on the time reporting of your shell and run 't':
8.014r 8.020u 0.000s 100% 0M 0+0k 0st 0+0io 74pf+0w
Means that the command took 8 seconds user CPU time and 8 seconds real time.
Now run cdrecord in RAW mode and run the command again:
18.309r 8.320u 5.370s 74% 0M 0+0k 0st 0+0io 74pf+0w
The real time now is 18.3 seconds.
REAL system load is: (1 - t_old/t_new)*100 = (1 - 8.014/18.309)*100 = 56.22%
Linus reports the folloging:
6:24.005r 54.860u 29.330s 21% 0M 0+0k 0st 0+0io 110pf+0w
for a 12x RAW write on the Athlon-1000 system.
You see this 'official' statistics for cdrecord from Linux is missing
110 seconds of system time!
The system load was 56% instead of the reported 21%.
This also shows what I can observe on this system: It is not possible
to write at 24x with this version of cdrecord and this CPU.
J�rg
EMail:[EMAIL PROTECTED] (home) J�rg Schilling D-13353 Berlin
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