Introduce pinned extents to contain unpurgeable pages

Some pages (e.g., hugetlb pages) cannot be purged, and should be
prioritized for reuse.  A custom extent_alloc hook signals this by
OR'ing EXTENT_ALLOC_FLAG_PINNED into the low bits of the returned
pointer; jemalloc strips the flag bits and caches pinned extents in
a dedicated ecache_pinned, separate from the dirty/muzzy decay
pipeline.

Pinned extents do not coalesce eagerly, except for ones larger than
SC_LARGE_MINCLASS.  A prefer-small policy reuses the smallest fitting
pinned extent, to avoid unnecessary split/fragmentation.
This commit is contained in:
Bin Liu
2026-04-19 22:56:22 -07:00
committed by Guangli Dai
parent 7638093c73
commit be2de8ccd8
22 changed files with 977 additions and 86 deletions

View File

@@ -246,6 +246,7 @@ TESTS_UNIT := \
$(srcroot)test/unit/hpa_vectorized_madvise_large_batch.c \
$(srcroot)test/unit/hpa_background_thread.c \
$(srcroot)test/unit/hpdata.c \
$(srcroot)test/unit/extent_alloc_flags.c \
$(srcroot)test/unit/huge.c \
$(srcroot)test/unit/inspect.c \
$(srcroot)test/unit/jemalloc_init.c \