2.4.18 kernels: no DMA w/ServerWorks LE chipsets
josip at icase.edu
Fri Aug 2 06:11:32 PDT 2002
I've just noticed that our Supermicro 370DLE motherboards with
ServerWorks LE chipset and dual UltraDMA/33 EIDE interfaces do NOT
enable DMA on ide-disk devices (under kernel 2.4.18-5smp, RedHat
distribution). This is puzzling, because DMA worked just fine until
recently (I think). Unfortunately, enabling DMA manually under the
2.4.18-5smp kernel ("hdparm -d1 /dev/hda") can lock up the system.
Apparently, others have had this problem too
speculates that 2.4.18 drops out of DMA due to a hardware bug in
ServerWorks OSB4 which at least some older kernels did not trigger).
As a consequence, we get only 3.5-4.5 MB/s on these disks instead of
12-22 MB/s which should be the norm.
It appears that this new kernel problem has not been fixed yet...
Dr. Josip Loncaric, Research Fellow mailto:josip at icase.edu
ICASE, Mail Stop 132C PGP key at http://www.icase.edu./~josip/
NASA Langley Research Center mailto:j.loncaric at larc.nasa.gov
Hampton, VA 23681-2199, USA Tel. +1 757 864-2192 Fax +1 757 864-6134
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