[PlanetCCRMA] Configuring 2.6.11-0.3.rdt.rhfc2.ccrma for 0 xruns...

[Mark Knecht]

On 13 Apr 2005 11:11:15 -0700, Fernando Lopez-Lezcano
<nando@ccrma.stanford.edu> wrote:

> > [root@Godzilla root]# /etc/init.d/rtirq status
> >
> >   PID CLS RTPRIO  NI PRI %CPU STAT COMMAND
> >   242 FF      80  -5 120  0.0 SW<  IRQ 8
> >    20 FF      60  -5 100  0.0 SW<  IRQ 9
> >   407 FF      60  -5 100  0.0 SW<  IRQ 5
> >   961 FF      59  -5  99  0.1 SW<  IRQ 11
> >   344 FF      50  -5  90  0.0 SW<  IRQ 1
> >   263 FF      49  -5  89  0.0 SW<  IRQ 12
> >   303 FF      46  -5  86  0.0 SW<  IRQ 14
> >   305 FF      45  -5  85  0.0 SW<  IRQ 15
> >   411 FF      42  -5  82  0.0 SW<  IRQ 10
> >   2152 FF      40  -5  80  0.0 SW<  IRQ 7
> >   2179 FF      39  -5  79  0.0 SW<  IRQ 4
> >   2180 FF      38  -5  78  0.0 SW<  IRQ 3
> >   3266 FF      37  -5  77  0.0 SW<  IRQ 6
> >
> > [root@Godzilla root]#
> >
> > NOTE: I would think that I'd want IRQ11 to be the highest priority
> > behind system functions, followed by IRQ's 5 & 10 to give me fast disk
> > access. How can I accomplish this?
> 
> You can change the priorities yourself using the "chrt" command, for
> example:
>   chrt -f -p 43 411
> (should change pid 411 to "f"ifo priority 43)
> -- Fernando

Fernando,
   Thanks for the hints. A few questions:

1) Is any of this chrt stuff sticky? Or is this something I'd have to
do every time I boot?

2) What is 'fifo priority'?

3) Which way is 'higher priority'? 80 or 37.

4) What's the difference between RTPRIO and PRI?

After my reboot it seems that these status is almost nonsensical. Why
is IRQ10 so high? (Assuming high numbers mean high priority.)

 [root@Godzilla root]# /etc/init.d/rtirq status
 
  PID CLS RTPRIO  NI PRI %CPU STAT COMMAND
  242 FF      80  -5 120  0.0 SW<  IRQ 8
  407 FF      60  -5 100  0.3 SW<  IRQ 10
 1151 FF      60  -5 100  0.0 SW<  IRQ 5
   20 FF      59  -5  99  0.5 SW<  IRQ 9
  344 FF      50  -5  90  0.0 SW<  IRQ 1
  263 FF      49  -5  89  0.0 SW<  IRQ 12
  303 FF      46  -5  86  0.0 SW<  IRQ 14
  305 FF      45  -5  85  0.0 SW<  IRQ 15
  411 FF      42  -5  82  0.2 SW<  IRQ 11
 2533 FF      40  -5  80  0.0 SW<  IRQ 7
 2555 FF      39  -5  79  0.0 SW<  IRQ 4
 2556 FF      38  -5  78  0.0 SW<  IRQ 3
 4061 FF      37  -5  77  0.0 SW<  IRQ 6
 
[root@Godzilla root]# cat /proc/interrupts
           CPU0
  0:    2665407          XT-PIC  timer  0/65407
  1:       3583          XT-PIC  i8042  0/3583
  2:          0          XT-PIC  cascade  0/0
  7:          1          XT-PIC  parport0  0/1
  8:          1          XT-PIC  rtc  0/1
  9:     398235          XT-PIC  acpi, hdsp  0/98235
 10:     790661          XT-PIC  ohci1394, eth0  0/90661
 11:     385876          XT-PIC  ohci1394  0/85876
 12:      91249          XT-PIC  i8042  1/91249
 14:      25616          XT-PIC  ide0  0/25615
 15:         51          XT-PIC  ide1  1/50
NMI:          0
LOC:          0
ERR:          0
MIS:          0

I've tried changing dirty_expire_centisecs to 1000 and started a new
copy. 2 minutes in and no xruns so far at 128/2, but I'll need to go
the full 20 minutes to have more confidence. After that I'll try 64/2.

I do not understand these vm parameters....
Thanks,
Mark