From: Paolo Bonzini <pbonzini@redhat.com>
To: Gerhard Wiesinger <lists@wiesinger.com>,
qemu-devel@nongnu.org, Cole Robinson <crobinso@redhat.com>,
virt@lists.fedoraproject.org
Subject: Re: [Qemu-devel] Fedora FC21 - Bug: 100% CPU and hangs in gettimeofday(&tp, NULL); forever
Date: Tue, 13 Jan 2015 22:16:08 +0100 [thread overview]
Message-ID: <54B58B18.9060205@redhat.com> (raw)
In-Reply-To: <54B58AC0.5080805@wiesinger.com>
On 13/01/2015 22:14, Gerhard Wiesinger wrote:
>
> 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?
No, that's not possible. Unless you pause/resume or migrate the VM, all
of the handling of kvmclock is entirely in the kernel.
Paolo
next prev parent reply other threads:[~2015-01-13 21:16 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-08 13:36 [Qemu-devel] Fedora FC21 - Bug: 100% CPU and hangs in gettimeofday(&tp, NULL); forever Gerhard Wiesinger
2015-01-08 17:24 ` Paolo Bonzini
2015-01-08 18:12 ` Gerhard Wiesinger
2015-01-08 18:22 ` Paolo Bonzini
2015-01-08 22:28 ` Gerhard Wiesinger
2015-01-08 22:42 ` Paolo Bonzini
2015-01-12 11:41 ` Gerhard Wiesinger
2015-01-12 11:46 ` Paolo Bonzini
2015-01-12 11:53 ` Gerhard Wiesinger
2015-01-12 11:54 ` Paolo Bonzini
2015-01-13 20:13 ` Gerhard Wiesinger
2015-01-13 20:48 ` Paolo Bonzini
2015-01-13 21:08 ` Cole Robinson
2015-01-13 21:14 ` Gerhard Wiesinger
2015-01-13 21:16 ` Paolo Bonzini [this message]
2015-01-13 22:01 ` Gerhard Wiesinger
2015-01-14 0:59 ` Laine Stump
2015-01-14 9:15 ` Gerhard Wiesinger
2015-02-15 8:18 ` Gerhard Wiesinger
2015-02-16 14:18 ` Paolo Bonzini
2015-02-16 15:09 ` Gerhard Wiesinger
2015-02-16 15:29 ` Paolo Bonzini
2015-03-01 10:36 ` Gerhard Wiesinger
2015-03-02 9:26 ` Paolo Bonzini
2015-03-02 15:52 ` Gerhard Wiesinger
2015-03-02 17:15 ` Gerhard Wiesinger
2015-03-03 9:12 ` Gerhard Wiesinger
2015-03-03 10:12 ` Paolo Bonzini
2015-03-03 11:51 ` Gonglei
2015-03-03 12:28 ` Gerhard Wiesinger
2015-03-03 13:18 ` Gerhard Wiesinger
2015-03-03 20:50 ` Gerhard Wiesinger
2015-01-14 17:47 ` Juan Quintela
2015-01-14 17:52 ` Juan Quintela
2015-01-14 22:19 ` Gerhard Wiesinger
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