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From: Michael Forney <mforney@mforney.org>
To: 9front@9front.org
Subject: [9front] qemu clock/timer issue
Date: Fri, 4 Feb 2022 18:04:09 -0800	[thread overview]
Message-ID: <CAGw6cBvo+bA9BCOdXtM8O6vezod1szmVgKj0g-YnNYagf5++hw@mail.gmail.com> (raw)

I was recently running 9front in a VM on linux (qemu, with
-enable-kvm), and noticed several weird timing/clock issues. The date
command gives wildly varying results +- 1 minute:

cpu% date
Fri Feb  4 17:39:23 PST 2022
cpu% date
Fri Feb  4 17:39:12 PST 2022
cpu% date
Fri Feb  4 17:40:19 PST 2022
cpu% date
Fri Feb  4 17:39:18 PST 2022

`sleep 1` exits pretty much instantly, stats moves through the entire
width in a second or two, and clicking in scrollbars starts repeating

I notice the following messages in my dmesg:
kvm: vcpu 3: requested 38141 ns lapic timer period limited to 200000 ns
kvm: vcpu 1: requested 9449 ns lapic timer period limited to 200000 ns
kvm: vcpu 2: requested 51204 ns lapic timer period limited to 200000 ns
kvm: vcpu 0: requested 74421 ns lapic timer period limited to 200000 ns

I don't remember this problem last time I ran 9front in qemu (around a
year ago), so I looked through commit history and found one commit
that seemed like it might be related:

To check, I tried setting *nohpet=1 in my plan9.ini, which *seems* to
have solved the problem, though I still see those same messages in
dmesg on the linux host (but now the requested lapic timer period is
always around 100000 ns or greater).

Anyone know what's going on here?

             reply	other threads:[~2022-02-05  7:41 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-05  2:04 Michael Forney [this message]
2022-02-05 17:04 ` hiro
2022-02-05 18:14 ` Nick Owens
2022-02-18  3:25   ` Michael Forney
2022-02-21 22:35     ` cinap_lenrek

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