Date: Mon, 21 Apr 2008 12:01:29 -0700 From: "Murty, Ravi" <ravi.murty@intel.com> To: <freebsd-hackers@freebsd.org> Subject: Do you really "sleep" when blocked on a mutex? Message-ID: <AEBCFC23C0E40949B10BA2C224FC61B00704441C@orsmsx416.amr.corp.intel.com>
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Hello, =20 When a thread cannot get a mutex (default mutex) and needs to be blocked, is it really put to sleep? From looking at the code it appears that it is inhibited (TD_SET_LOCK) but isn't really put to sleep. =20 1. Why isn't it put to sleep - why can't it be treated the same? 2. The eventual question I am trying to answer is the difference between setrunnable() and setrunqueue() - this one simply finds a slot in the ksegrp and a runq to add the KSE/td. But setrunnable() also checks to see if the process is in memory (PS_INMEM) before calling sched_wakeup which eventually calls setrunqueue()? Why doesn't setrunqueue have to worry about the possibility that the process may have been swapped out while it was waiting to become runnable? =20 Thanks Ravi =20
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