Re: [perfmon] Re: [perfmon2] perfmon2 merge news

[Stephane Eranian]

Will,

On Tue, Nov 13, 2007 at 01:33:55PM -0500, William Cohen wrote:
> 
> The oprofile module can setup a handler for PMU interrupts. This is done in 
> archi/x86/oprofile/nmi_int:nmi_cpu_setup().  Other modules could do the 
> same. However, it bumps what ever was using the nmi/pmu off, then restores 
> nmi/pmu when oprofile is shut down. Maybe the pmu/nmi resource reservation 
> mechanism should be another self-contained patch.
> 

Oprofile does not setup the PMU interrupt. It builds on top of the NMI watchdog
setup. It uses the register_die() mechanism, if I recall. The low level APIC
and gate is setup elsewhere. Perfmon does not use NMI, unless forced to because
of the NMI watchdog. 


> >	- we could not support per-thread mode with the kernel module 
> >	approach due to
> >	  link to the context switch code. I do believe per-thread is a key 
> >	  value-add
> >	  for performance monitoring.
> 
> The per-thread monitoring is useful to a number of people and many people 
> want it. The thought was how to break the large perfmon patch into set of 
> smaller incremental patches. So it isn't whether to have per-thread pmu 
> virtualization, but rather when/how to get it in.

I think we all agree on this.

-- 

-Stephane
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/