From mboxrd@z Thu Jan  1 00:00:00 1970
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Thu, 09 May 2013 12:26:52 +0000
Subject: Re: [RFC][KVM][PATCH 1/1] kvm:ppc:booke-64: soft-disable interrupts
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To: Kevin Hao <haokexin@gmail.com>
Cc: Bhushan Bharat-R65777 <R65777@freescale.com>, "tiejun.chen" <tiejun.chen@windriver.com>, Caraman Mihai Claudiu-B02008 <B02008@freescale.com>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, Wood Scott-B07421 <B07421@freescale.com>, "agraf@suse.de" <agraf@suse.de>, "kvm-ppc@vger.kernel.org" <kvm-ppc@vger.kernel.org>, "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>

On Thu, 2013-05-09 at 16:21 +0800, Kevin Hao wrote:
> > Is it because that we cannot afford to lose perfmon interrupt for
> more accurate capturing of data ?
> 
> Yes, I think this will definitely improve the perf sample quality.

This is one of the primary reason why we implemented lazy disabling in
the first place and why I recently reworked it to decrease the periods
where we are hard disabled.

The other reasons are that storing bytes to the PACA is faster than
manipulating EE on many processors.

Cheers,
Ben.