I never quite understood why high disk I/O slowed the system so much. It's strange to me because I would expect the slow-down to affect only those processes dependent on the hard/optical drive data, but the slow-down affects even stuff loaded onto RAM. I'm here referring to iowait.
Why does the processor wait, instead of doing other work? Can anyone explain this limitation and why it hasn't been solved in Linux kernel? Is there a kernel out there that doesn't have this problem?
[note] There has been some progress in this performance area. For one, the later kernels (2.6.37 in my case) are much more responsive.