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Date: Wed, 7 Mar 2018 14:02:32 -0500
From: Steven Rostedt <rostedt@goodmis.org>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anton Blanchard <anton@samba.org>, Benjamin Herrenschmidt
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Subject: Re: [RFC PATCH 1/1] powerpc/ftrace: Exclude real mode code from
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On Thu, 08 Mar 2018 00:07:07 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:

> Yes, that's negligible.
> Though, to be honest, I will have to introduce a 'mfmsr' for the older 
> -pg variant. I still think that the improved reliability far outweighs 
> the minor slowdown there.

In that case, can you introduce a read_mostly variable that can be
tested before calling the mfmsr. Why punish normal ftrace tracing if
kvm is not enabled or running?

Both should probably have an #ifdef CONFIG_KVM encapsulating the code.

-- Steve