I have just upgraded from vbox 1.6 to 1.6.2 and I am experimenting with the suggestion on the user manual.
11.3. Linux guests 11.3.1. Linux guests may cause a high CPU load Some Linux guests may cause a high CPU load even if the guest system appears to be idle. This can be caused by a high timer frequency of the guest kernel. Some Linux distributions, for example Fedora, ship a Linux kernel configured for a timer frequency of 1000Hz. We recommend to recompile the guest kernel and to select a timer frequency of 100Hz. On the kernel make menuconfig under "Processor type and feature" -> "Timer frequency", I had it at 250Hz. I am currently lowering it to 100 Hz and will post improvements if any. -- Valmor > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:vbox-users- > [EMAIL PROTECTED] On Behalf Of Frank Mehnert > Sent: Friday, June 20, 2008 2:09 AM > To: [email protected] > Subject: Re: [vbox-users] VirtualBox.exe: 98% cpu usage > > On Thursday 19 June 2008, JD wrote: > > Stating the obvious that virtualization cannot be as fast > > as running on raw HW is not the issue at all. > > I would suggest you to read some papers about full virtualization > and first. > > > I am noticing 100% cpu utilization by VBox when I run > > apps on guest, which when run on host, do not use more > > than 15 - 20 % of cpu. So no matter what "optimizations" > > are implemented in VBox, I and others are seeing cpu > > utilization that is up to 5 times the utilization as when > > app is run on host. On V-Tech cpu's this is likely not as > > extreme. > > So, I am finding that virtualization in general > > is not very practical for these older non-VTech cpu's. > > The 100% CPU load you experience is a probably a bug which can be > fixed. Most people are satisfied with VirtualBox and its performance. > I guess there is some bad interaction between your hardware, your > host operating system and your guest. We have dozens of guests here > running very fast and showing a low CPU load on the host -- with > VT-x and AMD-V disabled. Note that some guests behave very unfriendly > to virtualization. Take Windows 3.x/95/98: These don't execute `hlt` > during the idle state (as modern operating systems do) but do > something like > > void reschedule() > { > for (;;) > { > thread_t *t = ready_list; > if (t) > switch_to(t); > else > /* ready list is empty -- nothing to do */ > ; > } > } > > Catching this case is obviously difficult as the VMM cannot know > if the guest is _really_ idle or if the guest does some calculation. > Try this endless loop on your host, you will experience a 100% CPU > load as well. Note, this was only an example. The reason for the > high load on your host might be different. > > I agree with Michael. You make statements here about virtualization > and its performance just from your observation but obviously without > any expertise. Please don't bitch people willing to help you. > > Kind regards, > > Frank > -- > Dr.-Ing. Frank Mehnert Sun Microsystems http://www.sun.com/ _______________________________________________ vbox-users mailing list [email protected] http://vbox.innotek.de/mailman/listinfo/vbox-users
