From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de (cantor2.suse.de [195.135.220.15]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mx2.suse.de", Issuer "CAcert Class 3 Root" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 8CCF6B703B for ; Fri, 20 Apr 2012 20:25:00 +1000 (EST) Subject: Re: [PATCH v4] KVM: PPC Use clockevent multiplier and shifter for decrementer Mime-Version: 1.0 (Apple Message framework v1257) Content-Type: text/plain; charset=us-ascii From: Alexander Graf In-Reply-To: <1334764879-18020-1-git-send-email-bharat.bhushan@freescale.com> Date: Fri, 20 Apr 2012 12:24:54 +0200 Message-Id: References: <1334764879-18020-1-git-send-email-bharat.bhushan@freescale.com> To: Bharat Bhushan Cc: Bharat Bhushan , linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, bharatb.yadav@gmail.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 Thanks, applied to kvm-ppc-next with fixed commit message and fixed = trailing whitespace :). Alex