The Design and Implementation of the Anykernel and Rump Kernels

A–24
RUMP_LWPROC(3) NetBSD Library Functions Manual RUMP_LWPROC(3)
rump kernels as well, but since rump uses the host’s thread and process
context directly, the rules for how thread context is determined are different.
In the rump model, each host thread (pthread) is either bound to a rump
kernel lwp or accesses the rump kernel with an implicit thread context
associated with pid 1. An implicit thread context is created every time
the rump kernel is entered and disbanded upon exit. While convenient for
occasional calls, creating an implicit thread uses a shared resource
which can become highly contended in a multithreaded situation. It is
therefore recommended that dedicated threads are created.
The association between host threads and the rump kernel curlwp is left
to the caller. It is possible to create a dedicated host thread for
every rump kernel lwp or multiplex them on top of a single host thread.
After rump lwps have been created, switching curlwp is very cheap --
faster than a thread context switch on the host. In case multiple
lwps/processes are created, it is the caller’s responsibility to keep
track of them and release them when they are no longer necessary. Like
other rump kernel resources, procs/lwps will be released when the process
hosting the rump kernel exits.
rump_pub_lwproc_rfork()
Create a process, one lwp inside it and set curlwp to the new lwp.
The flags parameter controls how file descriptors are inherited
from the parent. By default (flags=0) file descriptors are shared.
Other options are:
RUMP_RFFDG Copy file descriptors from parent. This is what
fork(2) does.
NetBSD 5.99.48 January 2, 2011 NetBSD 5.99.48