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From: Alexander Graf <agraf@suse.de>
To: Bharat Bhushan <r65777@freescale.com>
Cc: Bharat Bhushan <bharat.bhushan@freescale.com>,
	linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org,
	kvm-ppc@vger.kernel.org, bharatb.yadav@gmail.com
Subject: Re: [PATCH v4] KVM: PPC Use clockevent multiplier and shifter for decrementer
Date: Fri, 20 Apr 2012 12:24:54 +0200	[thread overview]
Message-ID: <F72D662F-4842-4CB3-841A-054DDCB1C360@suse.de> (raw)
In-Reply-To: <1334764879-18020-1-git-send-email-bharat.bhushan@freescale.com>


On 18.04.2012, at 18:01, Bharat Bhushan wrote:

> Time for which the hrtimer is started for decrementer emulation is =
calculated using tb_ticks_per_usec. While hrtimer uses the clockevent =
for DEC reprogramming (if needed) and which calculate timebase ticks =
using the multiplier and shifter mechanism implemented within clockevent =
layer. It was observed that this conversion (timebase->time->timebase) =
are not correct because the mechanism are not consistent. In our setup =
it adds 2% jitter.
>=20
> With this patch clockevent multiplier and shifter mechanism are used =
when starting hrtimer for decrementer emulation. Now the jitter is < =
0.5%.
>=20
> Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>

Thanks, applied to kvm-ppc-next with fixed commit message and fixed =
trailing whitespace :).


Alex

      reply	other threads:[~2012-04-20 10:25 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-04-18 16:01 [PATCH v4] KVM: PPC Use clockevent multiplier and shifter for decrementer Bharat Bhushan
2012-04-20 10:24 ` Alexander Graf [this message]

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