190 lines
5.5 KiB
Diff
190 lines
5.5 KiB
Diff
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Date: Fri, 3 Jul 2009 08:44:37 -0500
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Subject: mm: page_alloc reduce lock sections further
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/3.14/patches-3.14.0-rt1.tar.xz
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Split out the pages which are to be freed into a separate list and
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call free_pages_bulk() outside of the percpu page allocator locks.
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Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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---
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mm/page_alloc.c | 86 +++++++++++++++++++++++++++++++++++++++-----------------
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1 file changed, 61 insertions(+), 25 deletions(-)
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--- a/mm/page_alloc.c
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+++ b/mm/page_alloc.c
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@@ -662,7 +662,7 @@ static inline int free_pages_check(struc
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}
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/*
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- * Frees a number of pages from the PCP lists
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+ * Frees a number of pages which have been collected from the pcp lists.
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* Assumes all pages on list are in same zone, and of same order.
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* count is the number of pages to free.
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*
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@@ -673,15 +673,49 @@ static inline int free_pages_check(struc
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* pinned" detection logic.
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*/
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static void free_pcppages_bulk(struct zone *zone, int count,
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- struct per_cpu_pages *pcp)
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+ struct list_head *list)
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{
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- int migratetype = 0;
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- int batch_free = 0;
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int to_free = count;
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+ unsigned long flags;
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- spin_lock(&zone->lock);
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+ spin_lock_irqsave(&zone->lock, flags);
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zone->pages_scanned = 0;
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+ while (!list_empty(list)) {
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+ struct page *page = list_first_entry(list, struct page, lru);
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+ int mt; /* migratetype of the to-be-freed page */
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+
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+ /* must delete as __free_one_page list manipulates */
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+ list_del(&page->lru);
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+
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+ mt = get_freepage_migratetype(page);
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+ /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
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+ __free_one_page(page, zone, 0, mt);
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+ trace_mm_page_pcpu_drain(page, 0, mt);
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+ if (likely(!is_migrate_isolate_page(page))) {
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+ __mod_zone_page_state(zone, NR_FREE_PAGES, 1);
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+ if (is_migrate_cma(mt))
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+ __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
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+ }
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+
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+ to_free--;
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+ }
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+ WARN_ON(to_free != 0);
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+ spin_unlock_irqrestore(&zone->lock, flags);
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+}
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+
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+/*
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+ * Moves a number of pages from the PCP lists to free list which
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+ * is freed outside of the locked region.
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+ *
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+ * Assumes all pages on list are in same zone, and of same order.
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+ * count is the number of pages to free.
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+ */
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+static void isolate_pcp_pages(int to_free, struct per_cpu_pages *src,
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+ struct list_head *dst)
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+{
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+ int migratetype = 0, batch_free = 0;
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+
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while (to_free) {
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struct page *page;
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struct list_head *list;
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@@ -697,7 +731,7 @@ static void free_pcppages_bulk(struct zo
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batch_free++;
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if (++migratetype == MIGRATE_PCPTYPES)
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migratetype = 0;
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- list = &pcp->lists[migratetype];
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+ list = &src->lists[migratetype];
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} while (list_empty(list));
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/* This is the only non-empty list. Free them all. */
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@@ -705,35 +739,25 @@ static void free_pcppages_bulk(struct zo
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batch_free = to_free;
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do {
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- int mt; /* migratetype of the to-be-freed page */
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-
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page = list_last_entry(list, struct page, lru);
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- /* must delete as __free_one_page list manipulates */
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list_del(&page->lru);
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- mt = get_freepage_migratetype(page);
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- /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */
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- __free_one_page(page, zone, 0, mt);
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- trace_mm_page_pcpu_drain(page, 0, mt);
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- if (likely(!is_migrate_isolate_page(page))) {
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- __mod_zone_page_state(zone, NR_FREE_PAGES, 1);
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- if (is_migrate_cma(mt))
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- __mod_zone_page_state(zone, NR_FREE_CMA_PAGES, 1);
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- }
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+ list_add(&page->lru, dst);
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} while (--to_free && --batch_free && !list_empty(list));
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}
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- spin_unlock(&zone->lock);
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}
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static void free_one_page(struct zone *zone, struct page *page, int order,
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int migratetype)
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{
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- spin_lock(&zone->lock);
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&zone->lock, flags);
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zone->pages_scanned = 0;
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__free_one_page(page, zone, order, migratetype);
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if (unlikely(!is_migrate_isolate(migratetype)))
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__mod_zone_freepage_state(zone, 1 << order, migratetype);
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- spin_unlock(&zone->lock);
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+ spin_unlock_irqrestore(&zone->lock, flags);
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}
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static bool free_pages_prepare(struct page *page, unsigned int order)
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@@ -1236,6 +1260,7 @@ static int rmqueue_bulk(struct zone *zon
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void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
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{
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unsigned long flags;
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+ LIST_HEAD(dst);
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int to_drain;
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unsigned long batch;
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@@ -1246,10 +1271,11 @@ void drain_zone_pages(struct zone *zone,
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else
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to_drain = pcp->count;
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if (to_drain > 0) {
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- free_pcppages_bulk(zone, to_drain, pcp);
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+ isolate_pcp_pages(to_drain, pcp, &dst);
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pcp->count -= to_drain;
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}
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local_unlock_irqrestore(pa_lock, flags);
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+ free_pcppages_bulk(zone, to_drain, &dst);
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}
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#endif
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@@ -1268,16 +1294,21 @@ static void drain_pages(unsigned int cpu
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for_each_populated_zone(zone) {
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struct per_cpu_pageset *pset;
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struct per_cpu_pages *pcp;
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+ LIST_HEAD(dst);
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+ int count;
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cpu_lock_irqsave(cpu, flags);
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pset = per_cpu_ptr(zone->pageset, cpu);
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pcp = &pset->pcp;
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- if (pcp->count) {
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- free_pcppages_bulk(zone, pcp->count, pcp);
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+ count = pcp->count;
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+ if (count) {
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+ isolate_pcp_pages(count, pcp, &dst);
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pcp->count = 0;
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}
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cpu_unlock_irqrestore(cpu, flags);
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+ if (count)
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+ free_pcppages_bulk(zone, count, &dst);
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}
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}
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@@ -1416,8 +1447,13 @@ void free_hot_cold_page(struct page *pag
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pcp->count++;
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if (pcp->count >= pcp->high) {
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unsigned long batch = ACCESS_ONCE(pcp->batch);
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- free_pcppages_bulk(zone, batch, pcp);
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+ LIST_HEAD(dst);
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+
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+ isolate_pcp_pages(batch, pcp, &dst);
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pcp->count -= batch;
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+ local_unlock_irqrestore(pa_lock, flags);
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+ free_pcppages_bulk(zone, batch, &dst);
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+ return;
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}
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out:
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