Date: Wed, 16 Apr 2008 15:32:20 -0700 From: "Murty, Ravi" <ravi.murty@intel.com> To: <freebsd-hackers@freebsd.org> Subject: md_spinlock_count? Message-ID: <AEBCFC23C0E40949B10BA2C224FC61B006F81861@orsmsx416.amr.corp.intel.com>
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Hello All, =20 I was looking at the code that creates a new process (fork) with a single thread coming out on the other side. I can't figure out a couple of things. =20 1. Why is the md_spinlock_count for the new thread set to 1 and not to 0. This happens in cpu_fork and cpu_set_upcall under the amd64 tree.=20 2. If this was the "per-cpu" idle thread and the AP was booting up (running init_secondary) why does it grab sched_lock and call spinlock_exit. It would seem simpler to set the count of the idle thread to 0 and not have to call spinlock_exit. The only answer I can come up with is the fact that a non-zero spinlock_count prevents interrupts from getting disabled/renabled to some unknown value?=20 =20 Thanks Ravi Murty =20
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