arm64: lib: improve copy_page to deal with 128 bytes at a time

We want to avoid lots of different copy_page implementations, settling
for something that is "good enough" everywhere and hopefully easy to
understand and maintain whilst we're at it.

This patch reworks our copy_page implementation based on discussions
with Cavium on the list and benchmarking on Cortex-A processors so that:

  - The loop is unrolled to copy 128 bytes per iteration

  - The reads are offset so that we read from the next 128-byte block
    in the same iteration that we store the previous block

  - Explicit prefetch instructions are removed for now, since they hurt
    performance on CPUs with hardware prefetching

  - The loop exit condition is calculated at the start of the loop

Signed-off-by: Will Deacon <[email protected]>
Tested-by: Andrew Pinski <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>

0 files changed, 0 insertions, 0 deletions