Question on strategy() routines for 4.1BSD drivers

[Jim McGinness]

The invalid fill-on-demand-from-inode pages are made valid in uba or
mba maps by the other drivers before the transfer occurrs, then
validated by `pagein'.  Your driver should just validate the pages in
place and move the bytes.  It is probably necessary to raise your
priority while you do it, since another process running that image
might sneak in and find the valid page and try to execute the old
bytes.  Better would be to invert the sense of the `copyseg' routine
to move from physical address to user virtual address.

If you have memory to burn, however, I've found that it makes sense to
increase your number of buffers (and on 4.2 to increase bufpages).
This has the effect of keeping more of the disk in memory, but is not
as direct as targeting a particular file system to actually reside in
memory.
						Jim McGinness
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