K 10
svn:author
V 7
glebius
K 8
svn:date
V 27
2012-11-23T07:35:50.087543Z
K 7
svn:log
V 1125
  Introduce UMA_ZONE_PCPU zones.

  These zones have slab size == sizeof(struct pcpu), but request from
VM enough pages to fit (uk_slabsize * mp_ncpus). An item allocated
from such zone would have a separate twin for each CPU in the system, and
these twins are at a distance of sizeof(struct pcpu) from each other. This
magic value of distance would allow us to make some optimizations later.

  To address private item from a CPU simple arithmetics should be used:

  item = (type *)((char *)base + sizeof(struct pcpu) * curcpu)

  To introduce non-page size slabs a new field had been added to uma_keg
uk_slabsize. This shifted some frequently used fields of uma_keg to the
fourth cache line on amd64. To mitigate this pessimization, uma_keg fields
were a bit rearranged and least frequently used uk_name and uk_link moved
down to the fourth cache line. All other fields, that are dereferenced
frequently fit into first three cache lines.

  Right now kegs of such kind may have a large waste value, since
sizeof(struct pcpu) isn't a denominator of PAGE_SIZE. We plan to pad
struct pcpu appropriately to reduce this waste.

END