Messages in this thread | | | Date | Mon, 25 Mar 2024 23:50:08 +0000 | Subject | [RFC PATCH 0/9] zswap: store zero-filled pages more efficiently | From | Yosry Ahmed <> |
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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The series is based on a slightly outdated mm-unstable.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
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