VM idle page zeroing

[Matthew Dillon]

:Hi,
:
:This is my first attempt at a idle-time VM page zeroing. I added a kernel
:thread, 'zeroidle', which zeros pages as it has time.
:The patch is pretty rough at the minute.
:
:http://m-net.arbornet.org/users/sv5679/dfly/0001-vm-Add-idle-thread-to-pre-zero-pages.patch
:
:Any thoughts would be appreciated,
:-- vs
    
    Ok, we had a good conversation on IRC and there will be another
    iteration or two of this.  Essentially what needs to be done here
    is to detect that the cpu is needed for other things during the zeroing
    loop, use try_mplock() around the VM code, and a few other things
    to reduce the latency seen by other threads.

						-Matt