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0827a1fb14
During testing I found there are some times the zswap_writeback_entry()
return -ENOMEM, which is not we expected:
bpftrace -e 'kr:zswap_writeback_entry {@[(int32)retval]=count()}'
@[-12]: 1563
@[0]: 277221
The reason is that __read_swap_cache_async() return NULL because
swapcache_prepare() failed. The reason is that we won't invalidate zswap
entry when swap entry freed to the per-cpu pool, these zswap entries are
still on the zswap tree and lru list.
This patch moves the invalidation ahead to when swap entry freed to the
per-cpu pool, since there is no any benefit to leave trashy zswap entry on
the tree and lru list.
With this patch:
bpftrace -e 'kr:zswap_writeback_entry {@[(int32)retval]=count()}'
@[0]: 259744
Note: large folio can't have zswap entry for now, so don't bother
to add zswap entry invalidation in the large folio swap free path.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-2-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
71 lines
1.7 KiB
C
71 lines
1.7 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 u64 zswap_pool_total_size;
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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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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 is_zswap_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 is_zswap_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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