zsmalloc: record handle in page->private for huge object
We stores handle on header of each allocated object so it
increases the size of each object by sizeof(unsigned long).
If zram stores 4096 bytes to zsmalloc(ie, bad compression),
zsmalloc needs 4104B-class to store the data with handle.
However, 4104B-class has 1-pages_per_zspage so wasted size by
internal fragment is 8192 - 4104, which is terrible.
So this patch records the handle in page->private on such
huge object(ie, pages_per_zspage == 1 && maxobj_per_zspage == 1)
instead of header of each object so we could use 4096B-class,
not 4104B-class.
Signed-off-by: Minchan Kim <minchan@kernel.org>
1 file changed
