Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934056AbdDFJMC (ORCPT ); Thu, 6 Apr 2017 05:12:02 -0400 Received: from mx2.suse.de ([195.135.220.15]:33045 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933817AbdDFJLe (ORCPT ); Thu, 6 Apr 2017 05:11:34 -0400 Subject: Re: [PATCH] x86/xen/time: set ->min_delta_ticks and ->max_delta_ticks To: Nicolai Stange , Thomas Gleixner References: <20170326134403.16226-1-nicstange@gmail.com> <20170330200642.8228-1-nicstange@gmail.com> Cc: John Stultz , linux-kernel@vger.kernel.org, Boris Ostrovsky , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, xen-devel@lists.xenproject.org From: Juergen Gross Message-ID: <4a873fe9-ca70-b3bc-c101-f55ebc636a1b@suse.com> Date: Thu, 6 Apr 2017 11:11:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170330200642.8228-1-nicstange@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2627 Lines: 73 On 30/03/17 22:06, Nicolai Stange wrote: > In preparation for making the clockevents core NTP correction aware, > all clockevent device drivers must set ->min_delta_ticks and > ->max_delta_ticks rather than ->min_delta_ns and ->max_delta_ns: a > clockevent device's rate is going to change dynamically and thus, the > ratio of ns to ticks ceases to stay invariant. > > Make the x86 arch's xen clockevent driver initialize these fields properly. > > This patch alone doesn't introduce any change in functionality as the > clockevents core still looks exclusively at the (untouched) ->min_delta_ns > and ->max_delta_ns. As soon as this has changed, a followup patch will > purge the initialization of ->min_delta_ns and ->max_delta_ns from this > driver. > > Signed-off-by: Nicolai Stange Shall I carry this patch through the Xen tree or will it be processed via the tip tree? I'm fine with both variants. Juergen > --- > > Notes: > This prerequisite patch is part of a larger effort to feed NTP > corrections into the clockevent devices' frequencies and thus > avoiding their notion of time to diverge from the system's > one. If you're interested, the current state of the whole series > can be found at [1]. > > If you haven't got any objections and these prerequisites get > merged by 4.12 everywhere, I'll proceed with the remainder of > this series in 4.13. > > Applicable to next-20170324 as well as to John' Stultz tree [2]. > > [1] > git://nicst.de/linux.git cev-freq-adj.v10.fortglx-4.12-time > https://nicst.de/git/?p=linux.git;a=shortlog;h=refs/heads/cev-freq-adj.v10.fortglx-4.12-time > > [2] > https://git.linaro.org/people/john.stultz/linux.git fortglx/4.12/time > > arch/x86/xen/time.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c > index 1e69956d7852..7a3089285c59 100644 > --- a/arch/x86/xen/time.c > +++ b/arch/x86/xen/time.c > @@ -209,7 +209,9 @@ static const struct clock_event_device xen_timerop_clockevent = { > .features = CLOCK_EVT_FEAT_ONESHOT, > > .max_delta_ns = 0xffffffff, > + .max_delta_ticks = 0xffffffff, > .min_delta_ns = TIMER_SLOP, > + .min_delta_ticks = TIMER_SLOP, > > .mult = 1, > .shift = 0, > @@ -268,7 +270,9 @@ static const struct clock_event_device xen_vcpuop_clockevent = { > .features = CLOCK_EVT_FEAT_ONESHOT, > > .max_delta_ns = 0xffffffff, > + .max_delta_ticks = 0xffffffff, > .min_delta_ns = TIMER_SLOP, > + .min_delta_ticks = TIMER_SLOP, > > .mult = 1, > .shift = 0, >