Matthew Dillon wrote: > A virtualized kernel requires actually reserving the (memory) resources > beforehand, and it also guarentees that there won't be any resource > leakage or starvation. If you give a vkernel 64 MB of ram, that's all > it will use, period.
A few (dumb) questions, just out of curiosity ... When I start a qemu virtual machine with, say, 128 MB of RAM, then that memory is allocated to the qemu process in a normal way, i.e. it can also be paged to swap. If I understand you correctly, then DF's virtual kernels work differently: they delegate the allocations to the real kernel. Right? I guess that means that the memory of user processes running in the vkernel can be paged to swap, while the pages of the vkernel (its virtual KVM, so to speak) are locked to physical RAM, just like the real kernel. Is that correct? What about the cache (VM cache, buffer cache, whatever). During normal operation, a kernel tends to use almost all free RAM for the cache, i.e. there is almost zero free RAM. Do the virtual kernels behave the same? Do they even have their own caches? I guess what I'm really trying to ask is this: If I start 4 vkernels, each with 256 MB RAM, will they use 1 GB of real memory, even if only a few small processes run inside them? Unfortunately I currently don't have a spare machine to install -preview and play with vkernels myself. :-( Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing Dienstleistungen mit Schwerpunkt FreeBSD: http://www.secnetix.de/bsd Any opinions expressed in this message may be personal to the author and may not necessarily reflect the opinions of secnetix in any way.
