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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


[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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