Mark Cranness wrote: > I'm debugging a time sync / TSC problem and noted the following, which > looks like a bug: > > TM.cpp > function tmR3TimerQueueRunVirtualSync lines 1953 and 1986 > declare and use a variable fUpdateStuff. > It is initialised to false (line 1953) and tested for true (line > 1986), BUT NEVER set to true. > > http://www.virtualbox.org/browser/trunk/src/VBox/VMM/TM.cpp#L1953
This is a genuine bug, thanks for spotting it. I've fixed it internally and it should show up externally soon. > Won't this cause the TSC catchup to always fail (because the catch-up > calculation is not written back)? No, it's stopped further down in the same function after we've done the timeout callouts. I'm not actually sure if it's necessary to make these updates before we do the callouts - it's been a while since I worked on the code last. > There may be other functions that do this update instead, but a quick > look indicates that they might not. > > AND the behaviour of my VM indicates that the catch-up is not > happening as expected (or I am confused...). > > I set: > VBoxManage setextradata Server "VBoxInternal/TM/CatchUpStopThreshold" 30000000 > and > ... "VBoxInternal/TM/CatchUpStartThreshold3" 30000000 > ... "VBoxInternal/TM/CatchUpPrecentage3" 100 > So CatchUpStopThreshold is 30ms, and has a catch-up percent of +100% > and yet the catch-up fails with a "Giving up catch-up attempt at ..." > message, with timing that indicates NO catch-up is being applied at > all. The small parameter adjustment you did there won't help much on its own. And there are known issues with the catch-up not working correctly on certain setups. We're looking into the latter and there should eventually be fixed once we have it figured out... Thanks again for spotting the bug. -- Kind regards / Mit freundlichen Gruessen / Vennlig hilsen, Knut -- Sun Microsystems GmbH Knut St. Osmundsen Werkstrasse 24 Senior Staff Engineer, VirtualBox 71384 Weinstadt, Germany mailto:[email protected] ================================================ Sitz der Gesellschaft: Sun Microsystems GmbH, Sonnenallee 1, 85551 Kirchheim-Heimstetten Amtsgericht Muenchen: HRB 161028 Geschaeftsfuehrer: Thomas Schroeder, Wolfgang Engels, Wolf Frenkel Vorsitzender des Aufsichtsrates: Martin Haering ================================================ _______________________________________________ vbox-dev mailing list [email protected] http://vbox.innotek.de/mailman/listinfo/vbox-dev
