What are user threads?

Some articles on user threads, thread, user, user thread:

Light-weight Process - Performance
... LWPs are slower and more expensive to create than user threads ... LWP is created a system call must first be made to create a corresponding kernel thread, causing a switch to kernel mode ... These mode switches would typically involve copying parameters between kernel and user space, also the kernel may need to have extra steps to verify the parameters to check ...
Light-weight Process - Scheduler Activation
... While the user threading library will schedule user threads, the kernel will schedule the underlying LWPs ... Without coordination between the kernel and the thread library the kernel can make sub-optimal scheduling decisions ... Further, it is possible for cases of deadlock to occur when user threads distributed over several LWPs try to acquire the same resources that are used by another user thread that is not currently running ...

Famous quotes containing the words threads and/or user:

    All is waste and worthless, till
    Arrives the selecting will,
    And, out of slime and chaos, Wit
    Draws the threads of fair and fit.
    Ralph Waldo Emerson (1803–1882)

    A worker may be the hammer’s master, but the hammer still prevails. A tool knows exactly how it is meant to be handled, while the user of the tool can only have an approximate idea.
    Milan Kundera (b. 1929)