Subject: Re: Feedback requested on switching the exception wrapper used for the PMU interrupt on ppc64

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 14 May 2008 23:46:07 -0700

On Tue, 2008-05-13 at 15:26 -0700, Corey Ashford wrote:
> The perfmon2 code is available here: 
> http://sourceforge.net/project/showfiles.php?group_id=144822
> 
> perfmon2's interrupt handler does have a single entry point.  Could I 
> somehow mimic what the MASKABLE_EXCEPTION_PSERIES macro does inside
> of 
> the perfmon2 interrupt handler?  Are there examples of this I can look
> at?
> 
> That would give us the best of both worlds.

You can definitely snapshot as many data as you can, and if interrupts
are soft-disabled, just return to the caller, storing that snapshot in
some per-cpu data structure.

You can then add something to local_irq_restore() that checks whether
some perfmon2 stuff happened and does the actual storing of the data
that were previously collected.

Cheers,
Ben.