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From: dennisg@kgw2.bwi.WEC.COM (Dennis Glatting)
Newsgroups: comp.sys.next,comp.os.mach
Subject: technique used to implement mutex_lock()
Message-ID: <429@kgw2.bwi.WEC.COM>
Date: 16 Mar 90 18:48:46 GMT
Reply-To: dennisg@kgw2 ()
Followup-To: comp.sys.next
Distribution: na
Organization: Xetron Corporation, Cincinnati, Ohio
Lines: 14


how is mutex_lock() implemented in the NeXT computer?

i have several tasks with several threads each.  i had a thread lock a
mutex with mutex_lock() then, unfortunatly, died.  the mutex stayed locked.
i noticed that the NeXT was running a bit slow so i fired up gdb of
the task in question.  i found more than one thread in cthread_yield().
my question is:  when you call mutex_lock() and the mutex is locked then
what happens?  does the thread do a cthread_yield() until the mutex
is unlocked?  if that is true then why?  it seems a waste of cpu.

--
 dennisg@kgw2.bwi.WEC.COM   | Dennis P. Glatting
 ..!uunet!tron!kgw2!dennisg |