Timekeeping in stable/9
Martin Sugioarto
martin at sugioarto.com
Wed Jan 18 07:17:41 UTC 2012
Am Tue, 17 Jan 2012 20:12:51 +0000
schrieb Joe Holden <lists at rewt.org.uk>:
> Hi guys,
>
> Has anyone else noticed the tendency for 9.0-R to be unable to
> accurately keep time? I've got a couple of machines that have been
> upgraded from 8.2 that are struggling, in particular a Virtual box
> guest that was fine on 8.2, but now that's its been upgraded to 9.0
> counts at anything from 2 to 20 seconds per 5 second sample, the
> result is similar with HPET, ACPI-fast and TSC.
Hi Joe,
I can confirm this on VirtualBox. I've been running WinXP inside
VirtualBox and measured network I/O during downloads. It showed me very
high download rates (around 800kB/s) while it's physically possible to
download 200kB/s through DSL here (Germany sucks with DSL, even in
largest cities, btw!).
I correlated this behavior with high disk I/O on the host. That means
that the timer issues on the virtual host appear when I start a
larger cp job on the host. I also immediately thought that this has
something to do with timers.
You can perhaps try yourself and confirm, if it's the disk I/O that
influences timers. I somehow don't like the hard disk behavior. It
makes desktop unusable in some situations (mouse pointer skipping,
applications lock for several seconds).
> I also have physical boxes which new seem to drift quite
> substantially, ntpd cannot keep up and as these boxes need to be able
> to report the time relatively accurately, it is causing problems with
> log times and such...
Not sure about physical boxes. I have not taken a look at this, yet.
--
Martin
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