From owner-freebsd-virtualization@freebsd.org Wed Mar 1 17:48:20 2017 Return-Path: Delivered-To: freebsd-virtualization@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 8DD74CF2E08 for ; Wed, 1 Mar 2017 17:48:20 +0000 (UTC) (envelope-from amdmi3@amdmi3.ru) Received: from ihor-3.amdmi3.ru (ihor-3.amdmi3.ru [185.117.152.228]) by mx1.freebsd.org (Postfix) with ESMTP id 4245CCB1 for ; Wed, 1 Mar 2017 17:48:19 +0000 (UTC) (envelope-from amdmi3@amdmi3.ru) Received: from hive.panopticon (unknown [78.153.152.119]) by ihor-3.amdmi3.ru (Postfix) with ESMTPS id 081741AF142 for ; Wed, 1 Mar 2017 20:48:18 +0300 (MSK) Received: from hades.panopticon (hades.panopticon [192.168.0.32]) by hive.panopticon (Postfix) with ESMTP id F3977B4A for ; Wed, 1 Mar 2017 20:42:36 +0300 (MSK) Received: by hades.panopticon (Postfix, from userid 1000) id 67BF9C7C; Wed, 1 Mar 2017 20:46:40 +0300 (MSK) Date: Wed, 1 Mar 2017 20:46:40 +0300 From: Dmitry Marakasov To: freebsd-virtualization@freebsd.org Subject: Timer problems on FreeBSD 11R on KVM Message-ID: <20170301174640.GA44226@hades.panopticon> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: Mutt/1.7.2 (2016-11-26) X-BeenThere: freebsd-virtualization@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: "Discussion of various virtualization techniques FreeBSD supports." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 01 Mar 2017 17:48:20 -0000 Hi! I'm running a bunch of FreeBSD VMs on VPS provider which uses KVM. Recently one of them began bahaving strangely. Symptoms: - Much ~(30%) CPU spent in intr - top shows CPU used by "intr{swi4: clock (0)}" - kernel: calcru: runtime went backwards from 13958 usec to 10792 usec for pid 919 (sshd) messages in logs - There's no much load, no high network traffic, systat shows no excess interrupts. - This intr load is sporadic in form of ~30 minute busts each several hours - The box had ntpd running, but disabling it doesn't help - Playing with timer-related sysctls does not help either I've tried i8254 and TSC-low timecounters: kern.timecounter.hardware: ACPI-fast kern.timecounter.choice: TSC-low(800) i8254(0) ACPI-fast(900) dummy(-1000000) and kern.eventtimer.periodic=1 to no effect. I suspect that this began after some changes on the hoster's side. - This VM was working for more than a year without problems before - A graph which monitors a reply time of website running on that VM showed min. response time jump from 50 to 75 msec on Monday, after which problems began. So while I'm getting the hoster to tell me what they have changed, any ideas? -- Dmitry Marakasov . 55B5 0596 FF1E 8D84 5F56 9510 D35A 80DD F9D2 F77D amdmi3@amdmi3.ru ..: jabber: amdmi3@jabber.ru http://amdmi3.ru