#2869 closed defect (fixed)

Debian host, Debian guest: rdtsc goes backwards -> fixed in SVN/3.0.6

Reported by:	Markus Laker	Owned by:
Component:	VMM/HWACCM	Version:	VirtualBox 3.0.4
Keywords:	rdtsc backwards	Cc:
Guest type:	Linux	Host type:	Linux

Description

On Debian Lenny on a real PC, the attached program (rdtsc.cpp) works as expected. On Debian Lenny in VirtualBox 2.1.0 on Debian Lenny, the same program aborts after a few hundred thousand iterations, showing that rdtsc occasionally goes backwards. I've attached some sample output in output.txt.

If we ignore wrapping, rdtsc should only increase; it should never decrease.

Attachments (3)

rdtsc.cpp (1.0 KB ) - added by Markus Laker 16 years ago.: Demonstration program, to be compiled with G++
output.txt (706 bytes ) - added by Markus Laker 16 years ago.: Sample output when this program is run inside VirtualBox
VBox.log (41.2 KB ) - added by Markus Laker 16 years ago.: VBox.log, as requested

Download all attachments as: .zip

Change History (9)

by Markus Laker, 16 years ago

Attachment:	rdtsc.cpp added

Demonstration program, to be compiled with G++

by Markus Laker, 16 years ago

Attachment:	output.txt added

Sample output when this program is run inside VirtualBox

comment:1 by Sander van Leeuwen, 16 years ago

Attach your VBox.log too please.

by Markus Laker, 16 years ago

Attachment:	VBox.log added

VBox.log, as requested

comment:2 by Frank Mehnert, 16 years ago

Component:	other → VMM

comment:3 by Frank Mehnert, 16 years ago

Component:	VMM → VMM/HWACCM

Problem reproduced. Does not happen if VT-x / AMD-V is disabled.

comment:4 by Sander van Leeuwen, 15 years ago

Summary:	Debian host, Debian guest: rdtsc goes backwards → Debian host, Debian guest: rdtsc goes backwards -> fixed in SVN/3.0.6

comment:5 by Sander van Leeuwen, 15 years ago

Version:	VirtualBox 2.1.0 → VirtualBox 3.0.4

comment:6 by Frank Mehnert, 15 years ago

Resolution:	→ fixed
Status:	new → closed

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