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Sergey Senozhatsky authored
zsmalloc pool can be compacted concurrently by many contexts, e.g. cc1 handle_mm_fault() do_anonymous_page() __alloc_pages_slowpath() try_to_free_pages() do_try_to_free_pages( lru_gen_shrink_node() shrink_slab() do_shrink_slab() zs_shrinker_scan() zs_compact() Pool compaction is currently (basically) single-threaded as it is performed under pool->lock. Having multiple compaction threads results in unnecessary contention, as each thread competes for pool->lock. This, in turn, affects all zsmalloc operations such as zs_malloc(), zs_map_object(), zs_free(), etc. Introduce the pool->compaction_in_progress atomic variable, which ensures that only one compaction context can run at a time. This reduces overall pool->lock contention in (corner) cases when many contexts attempt to shrink zspool simultaneously. Link: https://lkml.kernel.org/r/20230418074639.1903197-1-senozhatsky@chromium.org Fixes: c0547d0b ("zsmalloc: consolidate zs_pool's migrate_lock and size_class's locks") Signed-off-by:
Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by:
Yosry Ahmed <yosryahmed@google.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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