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From: Olof Johansson <olof@lixom•net>
To: Mike Kravetz <kravetz@us•ibm.com>
Cc: Olof Johansson <olof@lixom•net>,
	linuxppc-dev@ozlabs•org, Paul Mackerras <paulus@samba•org>
Subject: Re: [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers
Date: Tue, 18 Jul 2006 22:33:00 -0500	[thread overview]
Message-ID: <20060719033300.GA9451@pb15.lixom.net> (raw)
In-Reply-To: <20060718231815.GC3091@w-mikek2.ibm.com>

On Tue, Jul 18, 2006 at 04:18:15PM -0700, Mike Kravetz wrote:

> I assume checking must be done at run time via something like,
> if (cpu_has_feature(CPU_FTR_PURR))

If you do it in the hcall asm instead (like Paulus suggested), then it's
better to use BEGIN_FTR_SECTION/END_FTR_SECTION() around it, that way
the PURR reads just get nopped out instead of adding tests and branches.

> Also assume that it would make sense to do this determination at
> initialization/boot time and put the result in the statistic data
> structure.  In this way we would know it is in the same cache line
> we are updating with other stats.  Or, should cur_cpu_spec->cpu_features
> be 'sufficiently hot' to make this a non-issue?

If you use the FTR_SECTION stuff then it'll be taken care of
automatically at boot time. Doing that from C is messy, I don't think
anyone has had reason to do it before.


-Olof

  reply	other threads:[~2006-07-19  3:37 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-18 20:47 [PATCH 0/3] powerpc: Instrument Hypervisor Calls Mike Kravetz
2006-07-18 20:48 ` [PATCH 1/3] powerpc: Instrument Hypervisor Calls: merge headers Mike Kravetz
2006-07-18 20:49 ` [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers Mike Kravetz
2006-07-18 22:34   ` Olof Johansson
2006-07-18 23:18     ` Mike Kravetz
2006-07-19  3:33       ` Olof Johansson [this message]
2006-07-19  3:50         ` Mike Kravetz
2006-07-18 20:50 ` [PATCH 3/3] powerpc: Instrument Hypervisor Calls: add debugfs files Mike Kravetz
2006-07-18 21:00 ` [PATCH 0/3] powerpc: Instrument Hypervisor Calls Paul Mackerras
2006-07-19  3:36   ` Mike Kravetz
2006-07-19 22:11     ` Mike Kravetz
2006-07-18 21:29 ` Mike Kravetz
2006-07-18 22:38   ` Olof Johansson
  -- strict thread matches above, loose matches on Subject: below --
2006-07-14 23:37 Mike Kravetz
2006-07-14 23:40 ` [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers Mike Kravetz
2006-07-15  0:15   ` Nathan Lynch
2006-07-15  0:41     ` Mike Kravetz
2006-07-15  8:03       ` Nathan Lynch
2006-06-22 22:56 [PATCH 0/3] powerpc: Instrument Hypervisor Calls Mike Kravetz
2006-06-22 22:58 ` [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers Mike Kravetz
2006-06-14  3:47 [PATCH 0/3] powerpc: Instrument Hypervisor Calls Mike Kravetz
2006-06-14  3:52 ` [PATCH 2/3] powerpc: Instrument Hypervisor Calls: add wrappers Mike Kravetz
2006-06-14  7:23   ` Arnd Bergmann
2006-06-14 14:42   ` Nathan Lynch
2006-06-14 22:33     ` Paul Mackerras
2006-06-14 22:40       ` Nathan Lynch
2006-06-14 23:52         ` Mike Kravetz
2006-06-15 11:09           ` Arnd Bergmann
2006-06-15 14:58             ` Mike Kravetz
2006-06-15 16:06               ` Arnd Bergmann
2006-06-16 16:11       ` Mike Kravetz

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