Embedded systems historically used hardware dedicated to
a specific task, as opposed to a more general purpose platform.
While GNU/Linux is growing in popularity outside of its
traditional server/workstation role, it remains ill-equipped for a
sub-millisecond hard real-time device. The ability of the kernel
to meet a deadline is predominantly a measure of process
dispatch latency (PDL). The Linux kernel by itself has no
latency guarantees at all, and PDL delays due to interrupt
handling easily exceed 100 ms. Created as a workstation operating
environment, the Linux scheduler tends to favor servicing
many simultaneous processes in a fashion that delivers quick
response time to a physical user. An embedded device by
comparison would rather preempt I/O tasks-like disk activity
in favor of servicing the real-time application and meeting the
timing deadline at stake.