Recently (I think it was yesterday) I saw a post by someone wondering
about an article from Sun lambasting the running of Linux on the z800. I
found this excellent refutation by Moshe Bar who also explains how he got
Linux S/390 running on his own personal box. An interesting read just for
that bit, I think.
"Sun's article also says that Linux is really designed for the PC
architecture (ostensibly, the x86) and not for other platforms such as the
mainframe's S/390. And another argument against Linux on the mainframe is
that the Linux virtual memory manager is not suited to run within a
virtual computer like z/VM because its generous allocation of buffer cache
conflicts with I/O buffers already allocated by z/VM for its guest OS.
"That is pure nonsense. In the 2.4 kernels, buffer cache utilization is
much lower than in previous versions; most stuff goes into the page cache.
Actual paging for most commercial applications is close to zero. RAM is
cheap and abundant. In many years of consulting I have yet to see a
production-duty Linux server paging in any significant amount. Add to that
z/VM's capability to restrict the RAM allocated to the guest machine and
Sun's argument becomes null and void."