This patch, courtesy Rick Lindsley, resolves long standing problem with disk statistics counters in 2.4 kernels.

Because of the bug in kernel, the counters would occasionally incorrectly report negative values. The patch has been tested against 2.4.24, but will probably apply on other versions, too. Thanks Rick!

Both runs have been done on a single 120GB 7200rpm IDE disk. Command used: iostat -x 5 (extended statistics, sample every 5 seconds).

iostat is a command line I/O performance monitoring utility. It is present in almost every major Unix flavor in use today, and here you can get the version for Linux.