From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH] nohz: disable traceback on NO_HZ warning Date: Mon, 14 Dec 2015 10:26:07 -0800 Message-ID: <1450117567-12173-1-git-send-email-stephen@networkplumber.org> Cc: dev@dpdk.org, "Charles \(Chas\) Williams" To: helin.zhang@intel.com, konstantin.ananyev@intel.com Return-path: Received: from mail-pa0-f42.google.com (mail-pa0-f42.google.com [209.85.220.42]) by dpdk.org (Postfix) with ESMTP id 5C01656A1 for ; Mon, 14 Dec 2015 19:26:01 +0100 (CET) Received: by pacdm15 with SMTP id dm15so107504682pac.3 for ; Mon, 14 Dec 2015 10:26:00 -0800 (PST) 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" 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 -- 2.1.4