Re: 2.6.x: iowait problem while burning a CD

[Paolo Ornati]

On Saturday 28 February 2004 23:39, Bill Davidsen wrote:
> >
> > At that point, mkisofs is probably running into a bazillion
> > small files, in subdirectories all over the place.
> >
> > Because a disk seek + track read takes 10ms, it's simply not
> > possible to read more than maybe 100 of these small files a
> > second, so mkisofs can't keep up.
>
> I certainly have seen this, although there is something odd in the
> process with large files as well. I sometimes see it in 2.4 as well, so
> it may be a characteristic of the application.
>
> What to do about it (things to try, not requirements):
>

I was talking about one big file... however:

> - use fs= to increase the size of the fifo a bit, remember to put "m"
>    after the buffer size or it will be taken in bytes. This helps with
>    the problem Rik describes

I have tried with 8 / 16 / 24 MB of buffer! (without big results)

> - be sure DMA is on the CD and the drive

yes

> - allow ints during io

yes

___________________________________________________________
/dev/hdc:
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  1 (on)
 readahead    = 256 (on)

/dev/hdc:

 Model=HL-DT-ST GCE-8400B, FwRev=1.03, SerialNo=
 Config={ Fixed Removeable DTR<=5Mbs DTR>10Mbs nonMagnetic }
 RawCHS=0/0/0, TrkSize=0, SectSize=0, ECCbytes=0
 BuffType=unknown, BuffSize=0kB, MaxMultSect=0
 (maybe): CurCHS=0/0/0, CurSects=0, LBA=yes, LBAsects=0
 IORDY=yes, tPIO={min:227,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4
 DMA modes:  mdma0 mdma1 *mdma2
 AdvancedPM=no
___________________________________________________________

> - I'm told deadline schedular but haven't tried it
> - get a new version of cdrecord, build with the 2.6 headers, use
>    ATAPI:/dev/hdX for dev= instead of ide-scsi (this is probably not
>    critical for data CD in 2.6.2 and later, ide-scsi seems to work)

I have never used IDE-SCSI with 2.6.x ;-)

> - use burn-free

yes


Bye

-- 
	Paolo Ornati
	Linux v2.6.3

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