Re: [Xen-devel] [PATCH 3/7] xen: rework locking for dump of scheduler info (debug-key r)

[Dario Faggioli <dario.faggioli@xxxxxxxxxx>]

On Tue, 2015-03-17 at 11:05 +0000, George Dunlap wrote:
> On 03/17/2015 10:54 AM, Jan Beulich wrote:

> > Finally, as said in different contexts earlier, I think unconditionally
> > acquiring locks in dumping routines isn't the best practice. At least
> > in non-debug builds I think these should be try-locks only, skipping
> > the dumping when a lock is busy.
> 
> You mean so that we don't block the console if there turns out to be a
> deadlock?
> 
> That makes some sense; but on a busy system that would mean a
> non-negligible chance that any give keystroke would be missing
> information about some cpu or other, which would be pretty frustrating
> for someone trying to figure out the state of their system.
> 
Mmm... that's a very good point, actually, which I did not think about.

> Would it make sense to have a version of spin_trylock for use in this
> kind of situation that waits & retries a reasonable number of times
> before giving up?
> 
Probably. After all, if one comes to the point of sending a debug-key,
he most likely want to see the system status at (almost) any cost...

Regards,
Dario

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