From owner-freebsd-stable@freebsd.org Tue Jan 23 15:40:55 2018 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 02C09ED9C2C for ; Tue, 23 Jan 2018 15:40:55 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-lf0-x22d.google.com (mail-lf0-x22d.google.com [IPv6:2a00:1450:4010:c07::22d]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 79C7082886 for ; Tue, 23 Jan 2018 15:40:54 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-lf0-x22d.google.com with SMTP id t139so1177242lff.0 for ; Tue, 23 Jan 2018 07:40:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=6791LFUdMussVrBAFHsud4R7FE3mvDzH7kq8Xq3AoVk=; b=MY/1gjMB3XtHYs5b2gUIVE2Ohehw13ErbJC2qJfIVtJ8eeYkAXLQ6n3HJ+ONabGDn7 9VcIjDnNfdnOC9La1/tJXxyaNf7A73P5ikDH+0fLd5DWUuSLv/w+3Ni2k0cDOFG9gePU gwqW3avBAo4MKoBq8UBzFFCwTTOiU4zarldoLWv75yVJOqNvjfhRNo/UHlwp5y/LyQWG dek5hg4VPHnEeoPd99CSt5GoROFkcjDawLa0YC+OXUWTRwUdIjL43fOYijjxe+09z42R ZPa3B7rfeNBFH7LrD4DdvLbf/qkKTN1iA5o6nxiqIKnAYb1I5c/oBUYd/H+nwpQ5a88b Q8Mw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=6791LFUdMussVrBAFHsud4R7FE3mvDzH7kq8Xq3AoVk=; b=UJUP/1xkQcJ2wBj9uNYrlkJVg0kFn4NHltJ1idHNJXhXrmbeD4A27CObynutJfCRns /wpE94/9SKg/N/pA1ZALovCMn94T+WhAa8RHxgNr068nKECpoTeabY2nNWbXY2tB8Pjw wI8OZ5nDQZvarQPf1K7mL/kLkN2H4+UH7sB3Yp6GFbkmrC3JFcojUlSLIdA/n91aqdUp J1gFXHgZmVwks3xurHpEhey6/dVDzQNH/LjPKmDTq9uE0HzQi0YYrG1FpsREKsA1xQPi 07x0wDKM9r833c9dkqZXG20pNmcRHqwmr0sjlWp5L15vdM/G5mtpMFE0iXAxG2hOf5U/ nZsQ== X-Gm-Message-State: AKwxytc3kVSJtRywpR8+x1wvNQn2twkXHVO5Rb/CFmVz3VpFyE2FbNhu Zo0t63SS0WCbs4LCAcKPwktVw576hqQePoNyS3o= X-Google-Smtp-Source: AH8x2270BSNFG9uq9taoUKVua1UrQZSluGXq6ocU0ONeOTG3UfRNp18JlISzJiN92NWmLM5MGKJHXI89oCi4M0AFqLY= X-Received: by 10.46.22.9 with SMTP id w9mr1383140ljd.91.1516722052396; Tue, 23 Jan 2018 07:40:52 -0800 (PST) MIME-Version: 1.0 Sender: asomers@gmail.com Received: by 10.179.87.131 with HTTP; Tue, 23 Jan 2018 07:40:51 -0800 (PST) In-Reply-To: <0b170dae-b816-ea49-3516-40bfd1deaa2a@bsquare.com> References: <0b170dae-b816-ea49-3516-40bfd1deaa2a@bsquare.com> From: Alan Somers Date: Tue, 23 Jan 2018 08:40:51 -0700 X-Google-Sender-Auth: hXnH5p4ZWRHe0KuRwT3MkOJKB6Q Message-ID: Subject: Re: Clock occasionally jumps backwards on 11.1-RELEASE To: Mike Pumford Cc: FreeBSD Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.25 X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 23 Jan 2018 15:40:55 -0000 On Tue, Jan 23, 2018 at 3:48 AM, Mike Pumford wrote: > On 22/01/2018 17:07, Alan Somers wrote: > >> Since upgrading my jail server to 11.1-RELEASE, the clock occasionally >> jumps backwards by 5-35 minutes for no apparent reason. Has anybody seen >> something like this? >> >> Details >> ===== >> >> * Happens about once a day on my jail server, and has happened at least >> once on a separate bhyve server. >> >> * The jumps almost always happen between 1 and 3 AM, but I've also seen >> them happen at 06:30 and 20:15. >> >> That's the window when the period scripts are run which if you have a > default configuration and a lot of jails will put the system under a lot of > stress. > That did not fail to escape my notice. However, none of the jails' periodic jobs involve the clock in any way. And I wouldn't think that a high CPU load could cause clock drift, could it? This isn't Windows XP, after all. > * I'm using the default ntp.conf file. >> >> Are you running ntpd inside the jail or on the jail host? On my jail > systems (which are 10.3 and 11.1) I run ntpd out the jail host (outside all > jails) and not inside the jails and the jails then get the accurate time as > the underlying host has accurate time. > Only on the host. New info: there is a possibility that my NFS server is hanging for awhile. That would explain my problem's timing. However, ntpd shouldn't be accessing any NFS shares, and I wouldn't think that a hung NFS server should be able to pause the clock. I'm doing a new experiment that should be more informative. But I'll have to wait until the problem recurs to learn anything. -Alan