flex_array: avoid divisions when accessing elements

On most architectures division is an expensive operation and accessing an
element currently requires four of them.  This performance penalty
effectively precludes flex arrays from being used on any kind of fast
path.  However, two of these divisions can be handled at creation time and
the others can be replaced by a reciprocal divide, completely avoiding
real divisions on access.

[[email protected]: rebase on top of changes to support 0 len elements]
[[email protected]: initialize part_nr when array fits entirely in base]
Signed-off-by: Jesse Gross <[email protected]>
Signed-off-by: Eric Paris <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Rientjes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions