On Wed, 14 Jul 1999, Neil A. Carson wrote:
> One thing that I was considering was making all binaries effectively
> PIC, and placing them at different points in the address space.
>
> An idea probably hated by unix hackers in general, but for small sets of
> processes it seemd an interesting way of preserving the cache between
> some context switches.
>
> Eg if we only allow a process 512MB of VA space, we can map each new
> pmap (sorry, a BSDism although I don't work on that any more either) at
> say 4KB + (512 * (i%6)) or something like that. Even with 1GB per proc
> you'd have enough room for 3...
>
> Thoughts?
>
This sounds like it would be possible. Another idea a colleague at work
suggested was to make everyone share the same virtual address mappings,
i.e. you don't have to flush the cache on a context switch. There would
be one set of virtual mappings that everyone gets mapped to.
Of course, another option (an idea even more hated than Neals, I'm
guessing:) would be to make Linux be able to handle a flat address
space. Then you can use the MMU for protection only, and have two sets
of page tables, one for the kernel, and one for everyone else. User
processes can then splat each other, but not the kernel. This makes the
system somewhat more functional than MS-DOS or MAC-OS.:) Not a popular
option, but for some occasions, this might be nice. (i.e. embedded
systems running Linux).
--
Kyle Mestery | StorageTek's Storage Networking Group
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