[vdr] Re: VDR recording problem

[Sergei Haller <Sergei.Haller@math.uni-giessen.de>]

On Mon, 17 Jan 2005, Richard Scobie (RS) wrote:

RS> 
RS> > > > UDMA modes: udma0 udma1 udma2 udma3 *udma4 udma5
RS> 
RS> And indeed the asterisked entry shows the drive is using UDMA66.

this is not an indicator for dma being enabled, as the following example 
shows:

   # sudo hdparm -d0 /dev/hda

   /dev/hda:
    setting using_dma to 0 (off)
    using_dma    =  0 (off)

   # hdparm /dev/hda

   /dev/hda:
    multcount    = 16 (on)
    IO_support   =  0 (default 16-bit)
    unmaskirq    =  0 (off)
    using_dma    =  0 (off)
    keepsettings =  0 (off)
    readonly     =  0 (off)
    readahead    = 256 (on)
    geometry     = 16383/255/63, sectors = 78140160, start = 0

   # hdparm -i /dev/hda

   /dev/hda:

    Model=ST94811A, FwRev=3.04, SerialNo=3KW0DP0K
    Config={ HardSect NotMFM HdSw>15uSec Fixed DTR>10Mbs RotSpdTol>.5% }
    RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
    BuffType=unknown, BuffSize=8192kB, MaxMultSect=16, MultSect=16
    CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=78140160
    IORDY=on/off, tPIO={min:240,w/IORDY:120}, tDMA={min:120,rec:120}
    PIO modes:  pio0 pio1 pio2 pio3 pio4
    DMA modes:  mdma0 mdma1 mdma2
    UDMA modes: udma0 udma1 udma2 udma3 udma4 *udma5
    AdvancedPM=yes: unknown setting WriteCache=enabled
    Drive conforms to: ATA/ATAPI-6 T13 1410D revision 2:

    * signifies the current active mode

as you can see, dma is disabled "using_dma = 0 (off)" 
but the asterisk is at "udma5"

and here is the timing difference:

   # sudo hdparm -t /dev/hda

   /dev/hda:
    Timing buffered disk reads:    8 MB in  3.10 seconds =   2.58 MB/sec

   # sudo hdparm -d1 /dev/hda

   /dev/hda:
    setting using_dma to 1 (on)
    using_dma    =  1 (on)

   # sudo hdparm -t /dev/hda

   /dev/hda:
    Timing buffered disk reads:   94 MB in  3.05 seconds =  30.81 MB/sec


hope, that helps



c ya
        Sergei
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