On Mon, Jun 12, 2000 at 06:31:52PM -0400, Greg Lindahl wrote:
>
> > The "spinlock stuck" message is just a debugging aid AFAIK,
>
> ... and I should also mention that I'm getting spinlock grabbed. Which is an
> error, not a warning.
I beg your pardon?
Both of those prints are part of the "debugging" code associated with
the SMP lock primitives. They are meant to be informative; the "stuck"
one indicates when a lock is being held for a long period of time
(relatively speaking, and essentially an arbitrary definition of "long").
The "grabbed" message simply indicates when a process that was "stuck"
actually got the lock. The "ticks" indicated are jiffies, of course,
and on ALPHA there are usually 1024/second, so when a "grabbed"
message is printed saying it waited for 6732 ticks, that's 6+ seconds.
That seemed awful long to me when I first saw it, so I asked either
Linus or Alan about it, and they said it was "normal" or "reasonable",
so I stopped worrying. Perhaps it's time to ask again, though I'd be
quite worried if I saw that much time on a 2.4.xx kernel... ;-}
In addition, the "stuck" and "grabbed" messages indicate on which CPU
the "stickee" and the "owner" are running. If you see a bunch of "stuck"
messages with the same owner/CPU, they're all waiting for that one.
If you see a bunch of "stuck" messages, and no "grabbed", THAT is a
problem, ie usually the owner/CPU has died some horrible death without
releasing the lock, and no progress can ever be made - you're hosed.
Is this what you're seeing?
--Jay++
-----------------------------------------------------------------------------
Jay A Estabrook Alpha Engineering - LINUX Project
Compaq Computer Corp. - MRO1-2/K20 (508) 467-2080
200 Forest Street, Marlboro MA 01752 Jay.Estabrook@compaq.com
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