From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [PATCH] nohz: disable traceback on NO_HZ warning Date: Mon, 14 Dec 2015 11:13:11 -0800 Message-ID: <20151214111311.37a2e484@xeon-e3> References: <1450117567-12173-1-git-send-email-stephen@networkplumber.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit To: dev@dpdk.org Return-path: Received: from mail-pf0-f177.google.com (mail-pf0-f177.google.com [209.85.192.177]) by dpdk.org (Postfix) with ESMTP id 97FFEB62 for ; Mon, 14 Dec 2015 20:13:03 +0100 (CET) Received: by pfbu66 with SMTP id u66so65702740pfb.3 for ; Mon, 14 Dec 2015 11:13:03 -0800 (PST) Received: from xeon-e3 (static-50-53-82-155.bvtn.or.frontiernet.net. [50.53.82.155]) by smtp.gmail.com with ESMTPSA id wo3sm44523867pab.25.2015.12.14.11.13.02 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 14 Dec 2015 11:13:02 -0800 (PST) In-Reply-To: <1450117567-12173-1-git-send-email-stephen@networkplumber.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, 14 Dec 2015 10:26:07 -0800 Stephen Hemminger wrote: > From: "Charles (Chas) Williams" > > A NO_HZ_FULL kernel needs to have a stable clock source like a non-stop > (or invariant) TSC. Unfortunately, this CPU feature/flag isn't advertised > by most hypervisors because they want the ability to migrate or save > virtual machines which would affect the TSC. > > This means that a kernel with NO_HZ_FULL configured would often generate > a kernel traceback on boot which causes users to generate false > alarms. NO_HZ_FULL is an optimization not a hard requirement. > Keep the message, just lose the traceback. > > Signed-off-by: Charles (Chas) Williams > Signed-off-by: Stephen Hemminger > --- > kernel/time/tick-sched.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 7c7ec45..2e1c90c 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -188,8 +188,8 @@ static bool can_stop_full_tick(void) > * Don't allow the user to think they can get > * full NO_HZ with this machine. > */ > - WARN_ONCE(tick_nohz_full_running, > - "NO_HZ FULL will not work with unstable sched clock"); > + if (tick_nohz_full_running) > + pr_notice_once("NO_HZ FULL will not work with unstable sched clock\n"); > return false; > } > #endif Never mind, wrong list