Getting Started with QNX Neutrino - QNX Software Systems

© 2009, QNX Software Systems GmbH & Co. KG. The kernel’s role
If the state is:
CONDVAR
DEAD
INTR
JOIN
MUTEX
NANOSLEEP
NET_REPLY
NET_SEND
READY
RECEIVE
REPLY
RUNNING
SEM
SEND
SIGSUSPEND
SIGWAITINFO
STACK
STOPPED
WAITCTX
WAITPAGE
WAITTHREAD
The thread is:
Waiting for a condition variable to be signaled.
Dead. Kernel is waiting to release the thread’s resources.
Waiting for an interrupt.
Waiting for the completion of another thread.
Waiting to acquire a mutex.
Sleeping for a period of time.
Waiting for a reply to be delivered across the network.
Waiting for a pulse or message to be delivered across the network.
Not running on a CPU, but is ready to run (one or more higher or
equal priority threads are running).
Waiting for a client to send a message.
Waiting for a server to reply to a message.
Actively running on a CPU.
Waiting to acquire a semaphore.
Waiting for a server to receive a message.
Waiting for a signal.
Waiting for a signal.
Waiting for more stack to be allocated.
Suspended (SIGSTOP signal).
Waiting for a register context (usually floating point) to become
available (only on SMP systems).
Waiting for process manager to resolve a fault on a page.
Waiting for a thread to be created.
The important thing to keep in mind is that when a thread is blocked, regardless of
which state it’s blocked in, it consumes no CPU. Conversely, the only state in which a
thread consumes CPU is in the RUNNING state.
We’ll see the SEND, RECEIVE, and REPLY blocked states in the Message Passing
chapter. The NANOSLEEP state is used with functions like sleep(), which we’ll look at
in the chapter on Clocks, Timers, and Getting a Kick Every So Often. The INTR state
is used with InterruptWait(), which we’ll take a look at in the Interrupts chapter. Most
of the other states are discussed in this chapter.
April 30, 2009 Chapter 1 • Processes and Threads 25