I'm running a setup consisting of a Linux host OS and a Windows 7 guest (VMware Workstation). I'm trying to run 16 CPU-bound background jobs on the Linux host at nice values of 19 (the lowest possible priority; one for each virtual CPU) and simultaneously use the Windows VM as a normal desktop OS. For some reason the Linux background jobs make my Windows VM grind to a halt even though VMware's nice value is 0.
If it helps, I'm running an 8-core machine with hyperthreading, so 16 virtual CPUs. Since VMware Workstation only supports virtualizing 8 cores, only 8 of the cores are visible in the Windows guest.
Edit: The background jobs I'm running are almost purely CPU bound and perform virtually no I/O.
Edit # 2: It's not an issue with hyperthreading messing up scheduling. Disabling hyperthreading in the BIOS solves nothing.