On 06/28/2009 10:05 PM, Erik Jacobson wrote:
* In some of the timing runs on this system, the "real time" reported by
the time command was off by 10 to 11 times. Issues were found in
the messages file that seemed to relate to this including HUGE time
adjustments by NTP and kernel hrtimer 'interrupt too slow' messages.
This specific problem seems to be intermittent.
This is on the host? It can easily ruin your day.
This was in the guest.
Ok. Please keep ntp off in the guest and verify the guest says it uses
kvmclock.
Can you post kvm_stat output during the run?
Sure, I'll try to get time on the system again next week and post in
to the thread again. We'll still have the issue with the non-sequential
nodes and incorrect representation of memory for this two-socket
Nehalem system. I don't think that patch has made it in to the kernel.
Thanks for replying back.
If you have any other things you'd suggest trying, I'm game to give it a
whirl. Someone suggested trying to export a whole PCI device to the guest.
I won't be able to do that on this machine, maybe later when I have physical
access to the system. Besides, that exercise might not poke at what I'm
interested in anyway.
Shouldn't be needed. It's sufficient to export an LVM volume with
cache=none:
-drive file=/dev/vg/lv,cache=none,if=virtio
Others suggested some potential settings EPT (Extended Page Table) and
VPID (Virtual Path Identifier?) but I don't see where these settings are
exposed (they aren't, for example, in this system's BIOS).
Look in /sys/modules/kvm_intel/paramters, ept and vpid should default to
enabled.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
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