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Date: Sat, 15 Jul 2006 22:53:54 -0500
To: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 0/3] powerpc: Instrument Hypervisor Calls
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From: Olof Johansson <olof@lixom.net>
Cc: Bryan Rosenburg <rosnbrg@us.ibm.com>, linuxppc-dev@ozlabs.org,
	Nathan Lynch <ntl@pobox.com>, Paul Mackerras <paulus@samba.org>,
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On Sat, Jul 15, 2006 at 02:00:02AM +0200, Arnd Bergmann wrote:

> What happened to the question whether to use PURR values for also measuring
> cycles spent executing the hcall as opposed to cycles that passed before
> the hcall returns. Did that turn out not giving extra information after all
> or was there a different reason to drop that idea?

Just so people don't forget: this can't be done on all processors. For
example, PPC970 and POWER4 don't implement the PURR SPR. And it doesn't
make sense to use H_PURR to get the software emulated ones there. Not
really an issue on POWER4 since they don't do shared processor LPAR, but
on JS21 I think they might do?


-Olof