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[Qemu-devel] Is 'hwclock -u -s' in a modern Linux guest necessary?
From: |
Richard W.M. Jones |
Subject: |
[Qemu-devel] Is 'hwclock -u -s' in a modern Linux guest necessary? |
Date: |
Sat, 19 Mar 2016 19:32:44 +0000 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
I've been examining the time taken to launch the libguestfs appliance[1].
One of the commands we run in our custom init is:
hwclock -u -s
This takes 0.3 seconds, which is over 10% of the total launch time,
and as far as I can tell it does nothing useful. It was added many
years ago, and no one knows what it does.
We can assume that we're running a modern Linux guest kernel, recent
qemu, have virtio, kvm-clock etc. Is there any need to run this
command?
Rich.
[1] http://libguestfs.org/guestfs-internals.1.html
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
libguestfs lets you edit virtual machines. Supports shell scripting,
bindings from many languages. http://libguestfs.org
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