SMP spin_lock...

©[@ÄØÿ¿8þÿ¿Gerd Knorr (moyer@mclinux.com)
Mon, 14 Feb 2000 16:45:27 -0500 (EST)


==> Regarding SMP spin_lock...; Robert Dinse <nanook@eskimo.com> adds:

nanook> I wish there were an option to recover from spin_lock deadlock
nanook> conditions, when one times out, release the lock and get on with
nanook> life or something. Yes, I realize the potential for file or memory
nanook> corruption exists, but file corruption potential also exists when
nanook> data cached and not yet written to disk is lost due to the need to
nanook> hard-boot the machine when it hangs in spin_lock hell, and memory
nanook> corruption might crash the machine, well it's going to lock up and
nanook> die otherwise anyway.

Well, I believe SGI has a lockmetering package out there, and it
can be modified to do spin lock timeouts quite easily.
Unfortunately, this adds a bit of overhead to the kernel.

nanook> And if that can't be done, at the very least a panic and
nanook> reboot would be preferable to infinite hang.

Exactly. You may want to look into a watchdog card, or even the
software watchdog timer that already exists in the kernel.

Warmest Regards,

Jeff Moyer
Mission Critical Linux
http://www.missioncriticallinux.com

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