[RFC PATCH 0/1] zram: Allow rw_page when page isn't written back.

[Brian Geffon <bgeffon@google.com>]

Today when a zram device has a backing device we change the ops to
a new set which does not expose a rw_page method. This prevents the
upper layers from trying to issue a synchronous rw. This has the
downside that we penalize every rw even when it could possibly
still be performed as a synchronous rw.

This is just a proposal and I wanted to get feedback if people
felt this was worthwhile.

The motivation comes from what Minchan noted in the original
change which introduced the synchronous behavior that it enhanches
swap-in performance by about 45% [1]. So it'd be great if we could
still get this benefit while using writeback.

1. https://lore.kernel.org/all/1505886205-9671-5-git-send-email-minchan@kernel.org/

Brian Geffon (1):
  zram: Allow rw_page when page isn't written back.

 drivers/block/zram/zram_drv.c | 65 +++++++++++++++++++++--------------
 drivers/block/zram/zram_drv.h |  1 +
 2 files changed, 41 insertions(+), 25 deletions(-)

-- 
2.37.1.559.g78731f0fdb-goog