[linux-dvb] Evaluating why the short interruptions in recording

[Jan Panteltje <root@panteltje.demon.nl>]

I have been testing some things today regarding the short interruptions
in picture and sound.
It now seems (after writing in and output buffering), that these
interruptions are already present in the data from the saa7146,
so it is perhaps not a disk problem at all.
Anyways larger buffers, and you have these interruptions even if the HD light
is not even on, makes me think that it has to do with the data throughput
from the PCI bus via the saa7146 perhaps.
Is there any way to increase this data throughput?
Have been looking at saa7146_core.c for driver 0.82,
but I stll do not understand how it works.
This chip is on interrupt
           CPU0       
  0:   23563865          XT-PIC  timer
  1:     141158          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  4:     607510          XT-PIC  serial
 10:  144746103          XT-PIC  es1371
 11:     799987          XT-PIC  saa7146(1)
 13:          1          XT-PIC  fpu
 14:   16299587          XT-PIC  ide0
 15:       3299          XT-PIC  ide1

which has a low priority:
tblread: SYNTAX '           CPU0       '
irqtune: simulating IRQ priority of 0/8
tblread: SYNTAX '           CPU0       '
tblread: SYNTAX 'NMI:          0'
I00/P00:    23567573          XT-PIC  timer
I01/P01:      141279          XT-PIC  keyboard
I02/P02:           0          XT-PIC  cascade
I04/P11:      608004          XT-PIC  serial
I10/P04:   144746103          XT-PIC  es1371
I11/P05:      799987          XT-PIC  saa7146(1)
I13/P07:           1          XT-PIC  fpu
I14/P08:    16301243          XT-PIC  ide0
I15/P09:        3299          XT-PIC  ide1
irqtune: complete


Tested with the irqtune program, so priority 5.
irqtune does not work properly with my kernel version,
so I cannot seem to change the priority.
Does anyone know how to change this to priority 0?
I could not figure this out from the kernel sources.

Having such a low priority on the serial port can cause data loss, so why
not on a fast bus ?

Regards
Jan




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