V3.8.1 hd writing bug?

[fmfischer]

Hi, everyone,
write access to hd partitions has become very slow with KNOPPIX V3.8.1. The writing speed (measured with files > 2 x main memory and "dd" or "bonnie") is generally less than 15% compared to KNOPPIX V3.7 (with either 2.6 or 2.4 kernel) independent on fs (ext3, xfs, reiserfs). This I've measured on three systems so far. It is a sad case, since I liked to use KNOPPIX for repartitioning and full backup exercises especially in multi-disk systems.

BTW this problem does not appear on hd installations of KNOPPIX V3.8.1 .

Anyone any idea what could be the reason for this change to the worse with this version?

Michael

[fmfischer]

Ok: found the bug myself: unlike V3.7 and some earlier versions, V3.8.1 runs with "nodma" as default. So now one has to specify "dma" on the boot command line to get normal disk performance back.

Michael