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44c7c734a5
Each swapfile has one rb-tree to search the mapping of swp_entry_t to
zswap_entry, that use a spinlock to protect, which can cause heavy lock
contention if multiple tasks zswap_store/load concurrently.
Optimize the scalability problem by splitting the zswap rb-tree into
multiple rb-trees, each corresponds to SWAP_ADDRESS_SPACE_PAGES (64M),
just like we did in the swap cache address_space splitting.
Although this method can't solve the spinlock contention completely, it
can mitigate much of that contention. Below is the results of kernel
build in tmpfs with zswap shrinker enabled:
linux-next zswap-lock-optimize
real 1m9.181s 1m3.820s
user 17m44.036s 17m40.100s
sys 7m37.297s 4m54.622s
So there are clearly improvements.
Link: https://lkml.kernel.org/r/20240117-b4-zswap-lock-optimize-v2-2-b5cc55479090@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Chris Li <chriscli@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
70 lines
1.7 KiB
C
70 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(int type, pgoff_t offset);
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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(int type, pgoff_t offset) {}
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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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