Hi Roy,

>Can any of you guys explain to me what the heck a spinlock is?  I ran across i
> in a bit of c code in a magazine article,  dealing with something going on in
> the linux kernel...

> I've also run across the term in a number of other places.  The authors just
> seemed to assume that you'd know what they meant by that.

If I understand the term correctly, it appears to be a concept I'm familiar
with under different terminology. It's used in multi-threaded programming
to cause one thread to wait while another makes use of shared resources. 
For example,  assume a multi-threaded server where all threads share the
same logging routines, in order to prevent jumbled log entries access to
the logging routines has to be syncronized,  This can't be done using file
locking because all the threads are running in the same process. One of 
the ways this syncronization can be accomplished is by having a process
attempt to lock a memory location (variable).  If it obtains the lock, it
proceeds with the logging.  If it fails to obtain the lock, it waits
(sleeps, spins it's wheels) until the thread which holds the lock releases
it.  That's a simplified view since it ignores the potential for thread
starvation, deadlocks, etc...

Take care,
Janis

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