Very slow file read performance in kernel 2.4.26 or 2.6.8.1

[Andreas Kinzler]

Because of slow samba performance I did some testing on file read
performance and discovered that the read performance is very
poor sometimes.

dd if=/dev/hda6 of=/dev/null bs=65536

gives a raw read performance of approx. 41 MB/sec (which is perfectly OK).

Reading a file from the "filesystem", no matter if it is reiserfs or ext3
gives a read transfer rate of max. 25 MB/sec (best case).

I even had cases where a 730 MB file on a reiserfs partition was read
with approx. 3 MB/sec. That is pure horror.

Windows XP/SP2 on a similar system easily reaches 40 MB/sec on that same
730 MB file.

Any ideas? Or is the kernel that slow?

Regards

  Andreas

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