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Yosry Ahmed
2d4d2b1cfb
Add zswap_never_enabled() to skip the xarray lookup in zswap_load() if zswap was never enabled on the system. It is implemented using static branches for efficiency, as enabling zswap should be a rare event. This could shave some cycles off zswap_load() when CONFIG_ZSWAP is used but zswap is never enabled. However, the real motivation behind this patch is two-fold: - Incoming large folio swapin work will need to fallback to order-0 folios if zswap was ever enabled, because any part of the folio could be in zswap, until proper handling of large folios with zswap is added. - A warning and recovery attempt will be added in a following change in case the above was not done incorrectly. Zswap will fail the read if the folio is large and it was ever enabled. Expose zswap_never_enabled() in the header for the swapin work to use it later. [yosryahmed@google.com: expose zswap_never_enabled() in the header] Link: https://lkml.kernel.org/r/Zmjf0Dr8s9xSW41X@google.com Link: https://lkml.kernel.org/r/20240611024516.1375191-2-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Reviewed-by: Nhat Pham <nphamcs@gmail.com> Cc: Barry Song <baohua@kernel.org> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chris Li <chrisl@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_ZSWAP_H
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#define _LINUX_ZSWAP_H
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#include <linux/types.h>
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#include <linux/mm_types.h>
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struct lruvec;
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extern atomic_t zswap_stored_pages;
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#ifdef CONFIG_ZSWAP
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struct zswap_lruvec_state {
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/*
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* Number of pages in zswap that should be protected from the shrinker.
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* This number is an estimate of the following counts:
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*
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* a) Recent page faults.
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* b) Recent insertion to the zswap LRU. This includes new zswap stores,
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* as well as recent zswap LRU rotations.
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*
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* These pages are likely to be warm, and might incur IO if the are written
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* to swap.
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*/
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atomic_long_t nr_zswap_protected;
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};
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unsigned long zswap_total_pages(void);
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bool zswap_store(struct folio *folio);
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bool zswap_load(struct folio *folio);
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void zswap_invalidate(swp_entry_t swp);
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int zswap_swapon(int type, unsigned long nr_pages);
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void zswap_swapoff(int type);
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void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg);
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void zswap_lruvec_state_init(struct lruvec *lruvec);
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void zswap_folio_swapin(struct folio *folio);
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bool zswap_is_enabled(void);
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bool zswap_never_enabled(void);
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#else
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struct zswap_lruvec_state {};
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static inline bool zswap_store(struct folio *folio)
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{
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return false;
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}
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static inline bool zswap_load(struct folio *folio)
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{
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return false;
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}
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static inline void zswap_invalidate(swp_entry_t swp) {}
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static inline int zswap_swapon(int type, unsigned long nr_pages)
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{
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return 0;
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}
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static inline void zswap_swapoff(int type) {}
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static inline void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) {}
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static inline void zswap_lruvec_state_init(struct lruvec *lruvec) {}
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static inline void zswap_folio_swapin(struct folio *folio) {}
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static inline bool zswap_is_enabled(void)
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{
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return false;
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}
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static inline bool zswap_never_enabled(void)
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{
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return false;
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}
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#endif
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#endif /* _LINUX_ZSWAP_H */
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