From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51435) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YB8ne-0008Vi-4X for qemu-devel@nongnu.org; Tue, 13 Jan 2015 16:14:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YB8na-00042n-4K for qemu-devel@nongnu.org; Tue, 13 Jan 2015 16:14:54 -0500 Received: from vps01.wiesinger.com ([46.36.37.179]:44318) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YB8nZ-00042d-Tk for qemu-devel@nongnu.org; Tue, 13 Jan 2015 16:14:50 -0500 Message-ID: <54B58AC0.5080805@wiesinger.com> Date: Tue, 13 Jan 2015 22:14:40 +0100 From: Gerhard Wiesinger MIME-Version: 1.0 References: <54AE87C1.2060907@wiesinger.com> <54AEBD43.2060705@redhat.com> <54AEC877.9080600@wiesinger.com> <54AECAF3.3060909@redhat.com> <54AF047D.8010009@wiesinger.com> <54B3B2F5.1090405@wiesinger.com> <54B57C51.7090002@wiesinger.com> <54B584AB.4090303@redhat.com> In-Reply-To: <54B584AB.4090303@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Fedora FC21 - Bug: 100% CPU and hangs in gettimeofday(&tp, NULL); forever List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , qemu-devel@nongnu.org, Cole Robinson , virt@lists.fedoraproject.org On 13.01.2015 21:48, Paolo Bonzini wrote: > > On 13/01/2015 21:13, Gerhard Wiesinger wrote: >> It happens also with qemu-kvm 2.2.0 on another VM where also PostgreSQL >> is running: >> (gdb) bt >> #0 0x00007fff9a1feff4 in gettimeofday () >> #1 0x00000000006d425e in GetCurrentTimestamp () at timestamp.c:1274 >> >> What we know: >> OK : F20: 3.17.6-200.fc20.x86_64 on guest/host, >> qemu-kvm-1.6.2-10.fc20.x86_64 on host >> NOK: F21: 3.17.7-300.fc21.x86_64 on guest/host, >> qemu-kvm-2.1.2-7.fc21.x86_64 on host >> NOK: F21: 3.17.8-300.fc21.x86_64 on guest/host, >> qemu-kvm-2.2.0-1.fc21.x86_64 on host >> >> No one less can reproduce or has similar problems? >> Any further ideas? > Hmm, too bad. :( > > Any chance you can try with 1.7 and 2.0 releases? Cole, perhaps you > help building some RPMS for Gerhard? > Yes, I can try. RPMs would be fine. Don't know if it is related, but on another VM maschine I was getting the following 75s after reboot: [ 78.857006] INFO: rcu_sched self-detected stall on CPU { 0} (t=60000 jiffies g=1966 c=1965 q=0) [ 258.860006] INFO: rcu_sched self-detected stall on CPU { 0} (t=240003 jiffies g=1966 c=1965 q=0) I also had a look at the kernel code again: http://lxr.free-electrons.com/source/kernel/time/timekeeping.c?v=3.17#L493 499 do { 500 seq = read_seqcount_begin(&tk_core.seq); 501 502 ts->tv_sec = tk->xtime_sec; 503 nsecs = timekeeping_get_ns(&tk->tkr); 504 505 } while (read_seqcount_retry(&tk_core.seq, seq)); So it looks like that the seqcount always changes and therefore loops forever here (as far as I digged it down this is the only loop here). Might be something wrong with the memory barriers in recent qemu-kvm releases? Ciao, Gerhard