Саша е. Kernel preemption
In
recent years, concerns have arisen because of long latencies
associated with some kernel run-times, sometimes on the order of
100ms or more in systems with monolithic kernels. These latencies
often produce noticeable slowness in desktop systems, and can prevent
operating systems from performing time-sensitive operations such as
audio recording and some communications.[4]
Modern
operating systems extend the concepts of application preemption to
device drivers and kernel code, so that the operating system has
preemptive control over internal run-times as well. Under Windows
Vista,
the introduction of the Windows
Display Driver Model
(WDDM) accomplishes this for display drivers, and in Linux, the
preemptable kernel model introduced in version 2.6 allows all device
drivers and some other parts of kernel code to take advantage of
preemptive multi-tasking.
Under
Windows prior to Windows
Vista
and Linux
prior to version 2.6 all driver execution was co-operative, meaning
that if a driver entered an infinite loop it would freeze the system.
Disk access and file systems
Access
to data stored on disks is a central feature of all operating
systems. Computers store data on disks
using files,
which are structured in specific ways in order to allow for faster
access, higher reliability, and to make better use out of the drive's
available space. The specific way in which files are stored on a disk
is called a file
system,
and enables files to have names and attributes. It also allows them
to be stored in a hierarchy of directories or folders arranged in a
directory
tree.