This patch series drops the support for non-zero same-filled pages from zswap and makes storing zero-filled pages faster and more efficient. Non-zero same-filled pages should not be nearly as common as zero-filled pages, so dropping support for them in favor of improving the more common zero-filled pages makes sense. It also allows for a lot of code cleanups. Patch 1 is a small cleanup for zswap_store() cleanup path that also implies a small behavioral change. Patches 2-4 are groundword refactoring. Patch 5 removes the userspace tunable to enable same-filled pages handling. It arguably makes no sense anyway. Patch 6 drops the support for non-zero same-filled pages, and patch 7 allows for storing them more efficiently. Both of these patch cause around 1.4% improvement in the system time on kernbench. The kernel build test only produces around 1.5% zero-filled pages. Some real workloads are expected to have higher ratios of zero-filled pages and hence more improvement. They also save a little bit of memory. Exact numbers are in the commit logs. Patch 8 drops the limit checks before handling zero-filled pages and patch 9 does a followup cleanup of zswap_store() made possible by this series. This series is tagged as an RFC because it makes some potentially controversial decisions :) The series is based on a slightly outdated mm-unstable. Yosry Ahmed (9): mm: zswap: always shrink in zswap_store() if zswap_pool_reached_full mm: zswap: refactor storing to the tree out of zswap_store() mm: zswap: refactor limit checking from zswap_store() mm: zswap: move more same-filled pages checks outside of zswap_store() mm: zswap: remove zswap_same_filled_pages_enabled mm: zswap: drop support for non-zero same-filled pages handling mm: zswap: store zero-filled pages without a zswap_entry mm: zswap: do not check the global limit for zero-filled pages mm: zswap: use zswap_entry_free() for partially initialized entries mm/zswap.c | 297 +++++++++++++++++++++++++---------------------------- 1 file changed, 139 insertions(+), 158 deletions(-) -- 2.44.0.396.g6e790dbe36-goog
