149 lines
4.7 KiB
Diff
149 lines
4.7 KiB
Diff
From e604c3ccb4dfbdde2467fccef9bb36170a392695 Mon Sep 17 00:00:00 2001
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From: "T.J. Alumbaugh" <talumbau@google.com>
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Date: Wed, 18 Jan 2023 00:18:27 +0000
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Subject: [PATCH 18/19] UPSTREAM: mm: multi-gen LRU: simplify
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lru_gen_look_around()
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Update the folio generation in place with or without
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current->reclaim_state->mm_walk. The LRU lock is held for longer, if
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mm_walk is NULL and the number of folios to update is more than
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PAGEVEC_SIZE.
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This causes a measurable regression from the LRU lock contention during a
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microbencmark. But a tiny regression is not worth the complexity.
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Link: https://lkml.kernel.org/r/20230118001827.1040870-8-talumbau@google.com
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Change-Id: I9ce18b4f4062e6c1c13c98ece9422478eb8e1846
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Signed-off-by: T.J. Alumbaugh <talumbau@google.com>
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Cc: Yu Zhao <yuzhao@google.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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(cherry picked from commit abf086721a2f1e6897c57796f7268df1b194c750)
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Bug: 274865848
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Signed-off-by: T.J. Mercier <tjmercier@google.com>
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---
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mm/vmscan.c | 73 +++++++++++++++++------------------------------------
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1 file changed, 23 insertions(+), 50 deletions(-)
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--- a/mm/vmscan.c
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+++ b/mm/vmscan.c
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@@ -4573,13 +4573,12 @@ static void lru_gen_age_node(struct pgli
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void lru_gen_look_around(struct page_vma_mapped_walk *pvmw)
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{
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int i;
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- pte_t *pte;
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unsigned long start;
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unsigned long end;
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- unsigned long addr;
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struct lru_gen_mm_walk *walk;
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int young = 0;
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- unsigned long bitmap[BITS_TO_LONGS(MIN_LRU_BATCH)] = {};
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+ pte_t *pte = pvmw->pte;
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+ unsigned long addr = pvmw->address;
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struct folio *folio = pfn_folio(pvmw->pfn);
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struct mem_cgroup *memcg = folio_memcg(folio);
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struct pglist_data *pgdat = folio_pgdat(folio);
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@@ -4596,25 +4595,28 @@ void lru_gen_look_around(struct page_vma
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/* avoid taking the LRU lock under the PTL when possible */
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walk = current->reclaim_state ? current->reclaim_state->mm_walk : NULL;
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- start = max(pvmw->address & PMD_MASK, pvmw->vma->vm_start);
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- end = min(pvmw->address | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1;
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+ start = max(addr & PMD_MASK, pvmw->vma->vm_start);
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+ end = min(addr | ~PMD_MASK, pvmw->vma->vm_end - 1) + 1;
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if (end - start > MIN_LRU_BATCH * PAGE_SIZE) {
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- if (pvmw->address - start < MIN_LRU_BATCH * PAGE_SIZE / 2)
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+ if (addr - start < MIN_LRU_BATCH * PAGE_SIZE / 2)
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end = start + MIN_LRU_BATCH * PAGE_SIZE;
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- else if (end - pvmw->address < MIN_LRU_BATCH * PAGE_SIZE / 2)
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+ else if (end - addr < MIN_LRU_BATCH * PAGE_SIZE / 2)
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start = end - MIN_LRU_BATCH * PAGE_SIZE;
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else {
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- start = pvmw->address - MIN_LRU_BATCH * PAGE_SIZE / 2;
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- end = pvmw->address + MIN_LRU_BATCH * PAGE_SIZE / 2;
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+ start = addr - MIN_LRU_BATCH * PAGE_SIZE / 2;
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+ end = addr + MIN_LRU_BATCH * PAGE_SIZE / 2;
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}
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}
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- pte = pvmw->pte - (pvmw->address - start) / PAGE_SIZE;
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+ /* folio_update_gen() requires stable folio_memcg() */
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+ if (!mem_cgroup_trylock_pages(memcg))
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+ return;
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- rcu_read_lock();
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arch_enter_lazy_mmu_mode();
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+ pte -= (addr - start) / PAGE_SIZE;
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+
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for (i = 0, addr = start; addr != end; i++, addr += PAGE_SIZE) {
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unsigned long pfn;
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@@ -4639,56 +4641,27 @@ void lru_gen_look_around(struct page_vma
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!folio_test_swapcache(folio)))
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folio_mark_dirty(folio);
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+ if (walk) {
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+ old_gen = folio_update_gen(folio, new_gen);
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+ if (old_gen >= 0 && old_gen != new_gen)
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+ update_batch_size(walk, folio, old_gen, new_gen);
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+
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+ continue;
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+ }
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+
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old_gen = folio_lru_gen(folio);
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if (old_gen < 0)
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folio_set_referenced(folio);
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else if (old_gen != new_gen)
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- __set_bit(i, bitmap);
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+ folio_activate(folio);
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}
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arch_leave_lazy_mmu_mode();
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- rcu_read_unlock();
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+ mem_cgroup_unlock_pages();
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/* feedback from rmap walkers to page table walkers */
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if (suitable_to_scan(i, young))
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update_bloom_filter(lruvec, max_seq, pvmw->pmd);
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-
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- if (!walk && bitmap_weight(bitmap, MIN_LRU_BATCH) < PAGEVEC_SIZE) {
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- for_each_set_bit(i, bitmap, MIN_LRU_BATCH) {
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- folio = pfn_folio(pte_pfn(pte[i]));
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- folio_activate(folio);
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- }
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- return;
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- }
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-
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- /* folio_update_gen() requires stable folio_memcg() */
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- if (!mem_cgroup_trylock_pages(memcg))
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- return;
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-
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- if (!walk) {
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- spin_lock_irq(&lruvec->lru_lock);
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- new_gen = lru_gen_from_seq(lruvec->lrugen.max_seq);
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- }
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-
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- for_each_set_bit(i, bitmap, MIN_LRU_BATCH) {
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- folio = pfn_folio(pte_pfn(pte[i]));
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- if (folio_memcg_rcu(folio) != memcg)
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- continue;
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-
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- old_gen = folio_update_gen(folio, new_gen);
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- if (old_gen < 0 || old_gen == new_gen)
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- continue;
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-
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- if (walk)
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- update_batch_size(walk, folio, old_gen, new_gen);
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- else
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- lru_gen_update_size(lruvec, folio, old_gen, new_gen);
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- }
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-
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- if (!walk)
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- spin_unlock_irq(&lruvec->lru_lock);
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-
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- mem_cgroup_unlock_pages();
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}
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/******************************************************************************
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