make the Page stucture less than half its original size by getting rid of
the Lock and the lru.
The Lock was required to coordinate the unchaining of pages that where
both cached and on the lru freelist.
now pages have a single next pointer that is used for palloc.head
freelist xor for page cache hash chains in Image.pghash[].
cached pages are not on the freelist anymore, but will be reclaimed
from images by the pager when the freelist runs out of pages.
each Image has its own 512 hash chains for cached page lookup. That is
2MB worth of pages and there should be no collisions for most text images.
page reclaiming can be done without holding palloc.lock as the Image is
the owner of the page hash chains protected by the Image's lock.
reclaiming Image structures can be done quickly by only reclaiming pages from
inactive images, that is images which are not currently in use by segments.
the Ref structure has no Lock anymore. Only a single long that is atomically
incremented or decremnted using cmpswap().
there are various other changes as a consequence code. and lots of pikeshedding,
sorry.
the code was correct. erealloc9p() terminates the process
on error, but the code was handling realloc() error explicitely
and responded the request with Enomem error.
the vmware svga video card emulated by qemu (qemu -vga vmware) complains and eventually causes a panic if the rectangles aren't clipped.
messages like the following can be observed from qemu before the kernel panics:
vmsvga_update_rect: update h was < 0 (-20000)
vmsvga_update_rect: update height too large y: 10000, h: 0
vmsvga_update_rect: update w was < 0 (-20000)
vmsvga_update_rect: update width too large x: 10000, w: 0
i could only reproduce this in qemu 2.0.50 on the master branch, when using the ui and had selected 'Zoom To Fit' from the View menu.
fix bug introduced by amd64 support:
forgot to update ring index i on receive. surprisingly
this was working until there where more than one packet
to process. sorry.
ilock the controller while processing rings. this should
be fixed and use kprocs instead.
we have to make sure the *swap address* doesnt go away,
after putting the swap address in the segment pte.
after we unlock the segment, the process could be
killed or fault which would cause the swap address to
be freed *before* we write the page to disk when it
pulls the page from the cache and putswap() swap pte.
keeping a reference to the page is no good. we have
to hold on the swap address. this also has the advantage
that we can now test if the swap address is still
referenced and can avoid writing to disk.
as with the Block refcount changes, _xinc() and _xdec() arent
used anymore, so remove them.
architecure can still define ainc()/adec() when it needs them.
