KernelTrap: Interview: Nick Piggin

“Nick Piggin, a college student living in Canberra Australia,
has been working on an anticipatory I/O scheduler for the Linux
kernel.

“When a process reads data from a disk, the default ‘deadline’
I/O scheduler can offer poor performance if a streamed write is
happening at the same time. The reason is that many read operations
require multiple reads, each reporting a result back before the
next can be scheduled. Thus, each of these reads has to wait behind
a queue of writes, resulting in the aforementioned performance
problem. The anticipatory scheduler solves this problem nicely by
pausing for a few milliseconds after each read, ‘anticipating’ the
next read request.

“In this interview, Nick offers much more detail behind the
operation of the anticipatory scheduler. His goal is to stablize
and tune the new scheduler, aiming utimately for inclusion into the
2.5 development kernel tree as the default Linux I/O scheduler. The
latest version of Nick’s anticipatory scheduler can be found in
Andrew Morton’s -mm kernel branch…”

Complete
Story