[ros-kernel] Cache and memory manager

[Phillip S. <ps...@cf...>]

Who was it that recently did some work with the cache manager code?  Are 
you still working on it?  The Cc code needs to be reworked to use mapped 
section views like NT does instead of CACHE_SEGMENTs.  Currently, trying to 
copy a file on a machine with 8 megs of ram causes the cache to use all 
available memory, run out, and then the system locks up.  This is due to 
several reasons, the first being that the cache does not currently have any 
mechanism to prevent it from growing without bound.  The cache needs to map 
views of the files to be cached into the cache working set, and the working 
set and page fault handling code will keep the cache working set from 
growing without bound, as well as reclaiming cache memory.  The other bug 
in the current code is in cc/view.c in CcRosGetCacheSegment, which does this:

        Status = MmCreateVirtualMapping(NULL,
			      current->BaseAddress + (i * PAGESIZE),
			      PAGE_READWRITE,
			      (ULONG)MmAllocPage(0));

Note that the call to MmAllocPage is not checked for failure.  On my test 
system, it fails when memory runs out, and returns 0, which then gets 
passed to MmCreateVirtualMapping for the physical backing page.  If noone 
is working on this, I guess I'll go for it, but if someone already is, let 
me know.

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