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DAE performance

This is more to satisfy my curiosity than anything else, but maybe I
can help some folks out and learn something in the process. I've
recently started using my 450MHz G4 Cube (running woody with a
2.4.20-xfs-ben5 kernel) as a CD-ripping toaster. I'm using cdparanoia
III with ide-scsi to extract the audio, with jack as a front end. My
question is this: is it normal to see performance at around ~1.2 -
2.0x when ripping on a Cube? cdparanoia is using less than 4% of CPU,
so it doesn't seem to be swamped by I/O processing. I've done a bunch
of tweaking (upped the default DMA buffer, turned on Direct I/O), and
it doesn't seem to make much difference.

The combination of cdparanoia and LAME (--r3mix --nohist) results in
ripping and encoding taking ~110% the time that it would to play the
CD. I know that cdparanoia is, well, paranoid, but it seems a little
odd that I can get MP3s that sound just about the same out of iTunes
in about 10% of the time on my 500MHz original TiBook. Anyone have any
explanations or persuasive lies to account for the difference?

And if I play music through the Cube's USB speakers on top of ripping
and encoding, sound gets kind of rough (and the amount of CPU time
spent in kernel-land gets much higher). Is there any set of patches
that would improve this situation without harming ripping and encoding
performance overly?

(Details for the curious:

   1. Kernel is a stock 2.4.20-ben5 with only the XFS patches

   2. lsmod prints (most stuff is compiled into the kernel itself,
      followed xiph.org recommendations and didn't compile ide-cd

Module                  Size  Used by    Not tainted
ide-scsi                9824  15
sg                     30788   1 (autoclean)
af_packet              11400   2 (autoclean)
sd_mod                 12732   0 (autoclean) (unused)
hid                    15024   0 (unused)
sr_mod                 17588  28 (autoclean)
cdrom                  29728   0 (autoclean) [sr_mod]
scsi_mod               64128   4 (autoclean) [ide-scsi sg sd_mod sr_mod]

   3. cdparanoia -vsQ prints:

cdparanoia III release 9.8 (March 23, 2001)
(C) 2001 Monty <monty@xiph.org> and Xiphophorus

Report bugs to paranoia@xiph.org

Checking /dev/cdrom for cdrom...
        Testing /dev/cdrom for cooked ioctl() interface
                /dev/scsi/host0/bus0/target0/lun0/cd is not a cooked ioctl CDROM.
        Testing /dev/cdrom for SCSI interface
                generic device: /dev/scsi/host0/bus0/target0/lun0/generic
                ioctl device: /dev/scsi/host0/bus0/target0/lun0/cd

Found an accessible SCSI CDROM drive.
Looking at revision of the SG interface in use...
        SG interface version 3.1.24; OK.

CDROM model sensed sensed: MATSHITA DVD-ROM SR-8186 F113 

Checking for SCSI emulation...
        Drive is ATAPI (using SCSI host adaptor emulation)

Checking for MMC style command set...
        Drive is MMC style
        DMA scatter/gather table entries: 256
        table entry size: 65536 bytes
        maximum theoretical transfer: 7133 sectors
        Setting default read size to 13 sectors (30576 bytes).

Verifying CDDA command set...
        Expected command set reads OK.)


       . . . the self-reflecting image of a narcotized mind . . .
ozymandias G desiderata     ogd@aoaioxxysz.net     desperate, deathless
(415)823-6356       http://www.pushby.com/forrest/       ::AOAIOXXYSZ::

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