Hi all, I'm suffering from heavy performance issues more detailed explained in the forum[1] already. From what I've tested so far, there's a direct relationship to the amount of memory assigned to a VM, problem occurs with 48 GB of RAM, doesn't with 6, and it seems with the setting "largepages" of VirtualBox itself. Current tests show that with 48 GB of RAM in the VM and "largepages" enabled, the problem doesn't seem to occur as well.
That is interesting, because that setting doesn't seem to be enabled by default, the docs[2] only tell about ~5 % improvement, not that it's necessary at all for decent performance at some RAM size, and additionally there are circumstances in which "largepages" is ignored by VirtualBox[3] altogether. > 00:00:42.866663 PGMR3PhysAllocateLargePage: allocating large pages > takes too long (last attempt 103 ms; nr of timeouts 11); DISABLE https://www.virtualbox.org/attachment/ticket/16518/VBox_16518_5112.log#L1154 So is it possible that "largepages" itself really makes such a difference in performance after some amount of RAM assigned to a VM? If so, what's the threshold after which "largepages" is necessary instead of suggested/nice to have? Shouldn't that be mentioned in the docs then or that setting even be enabled by default at some amount of RAM? If "largepages" is necessary to get usable performance for some amount of RAM, why is it allowed to fail while continuing the VM? In my case the performance problems only occur after some runtime, maybe a few days, but they do occur at some time. Wouldn't it be better to stop starting the VM with some error message to give me the chance to make "largepages" work again by restarting the VM-host or such? That way I could be somewhat sure that the problem doesn't occur if the VM started properly. What does "largepages" do exactly? Is it only allocating some number of "huge pages" from the OS to reduce the number of pages to deal with? Is it preferring some "huge pages" size, like 2 MB in a default linux or 1 GB or doesn't care what "huge" means at all under some OS? How many of those pages is it allocating when, all needed according the VM-configuration at startup time or in chunks as needed during runtime like without "largepages"? Thanks for your time! [1]: https://forums.virtualbox.org/viewtopic.php?f=3&t=87904 [2]: https://www.virtualbox.org/manual/ch10.html#nestedpaging [3]: https://www.virtualbox.org/ticket/16518#comment:2 Mit freundlichen Grüßen, Thorsten Schöning -- Thorsten Schöning E-Mail: [email protected] AM-SoFT IT-Systeme http://www.AM-SoFT.de/ Telefon...........05151- 9468- 55 Fax...............05151- 9468- 88 Mobil..............0178-8 9468- 04 AM-SoFT GmbH IT-Systeme, Brandenburger Str. 7c, 31789 Hameln AG Hannover HRB 207 694 - Geschäftsführer: Andreas Muchow _______________________________________________ vbox-dev mailing list [email protected] https://www.virtualbox.org/mailman/listinfo/vbox-dev
