Re: realfeel4 for libpfm-3.0

From: Stephane Eranian <eranian_at_hpl.hp.com>
Date: 2004-03-31 04:42:28
Hi,

On Tue, Mar 30, 2004 at 02:07:59PM +0800, Zhu, Yi wrote:
> 
> I'm a user of realfeel4.
> 
> Recently SuSE ships SLES 9 beta with 2.6 kernel and libpfm-3.0.
> Since libpfm 3.0 changes its interface from 2.0, I cannot compile
> realfeel4.c. Do you have a version of realfeel4 that works on
> libpfm-3.0?
> 
I looked at your ported version of realfeel4.c. There were three
problems with it:

	- with the new perfmon interface, a system-wide context
	  is not automatically pinned to a CPU. You need an
	  explicit call to sched_setaffinity(). The perfmonctl()
	  calls, in this case, are only authorized from when the
	  calling tasking is running on the CPU that was used when
	  PFM_LOAD_CONTEXT was issued. To avoid problems it is always
	  best to explicitely call sched_setaffinity() prior to 
	  PFM_LOAD_CONTEXT.

	- for system-wide context, you currently cannot use
	  pfm_self_start()/pfm_self_stop() which are lighweight
	  versions of PFM_START/PFM_STOP. I am hoping to remove
	  this restrictions soon.

	- You had two calls to PFM_RESTART in you overflow handler.

The attached program does work for me.


-- 

-Stephane

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Received on Tue Mar 30 13:57:21 2004

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