VMM/Guest SMP: Very slow performance on over-commit

[Technologov]

Very slow performance when over-commit CPU.

Host = 1 CPU, Guest = 2 CPUs. (same happens with Host = 4 CPUs and guest with 8 CPUs)

Host: WinXP/32 and RHEL5/x64, Intel Core 2 Duo (2nd core disabled in BIOS), VBox 4.0.0

Guest: WinXP (problem happens even without GA)

Only one VM is running. XP boot takes longer than 20 minutes. I decided to kill VM.

-Technologov, 29.12.2010.

[Technologov]

VBox Log

[Technologov]

Host: Win 7 x64 + Intel Core i7 2600K CPU + VBox 4.1.0_BETA1

Guest: Debian Linux 6.0 x64 + 8-way SMP

Guest workload: Compiling VirtualBox.

*Host* OS becomes extremely unresponsive, like soft-lockup effect.

$ kmk

Workaround is to limit task to available _physical_ cores:

$ kmk -j4

(Host OS no longer locks-up)

-Technologov

[ramshankar]

You're not supposed to overcommit CPUs. Anyway, you probably already know that by now. Closing.